There are 10 planets and 12 houses in astrology, which make up the main part of any astrology chart. Because there are less planets than houses, this means every person has at least two houses in their natal chart with no planets in them (usually 3-5 houses). These houses that have no natal planets in them are called empty houses.
Every house in astrology governs a different part of yourself and your life, and the 1st house is the house of the self. What does it mean when your 1st house is empty
What is an empty house?
A natal chart is a snapshot of the locations of various planets, houses, and bodies in the Zodiac at the moment you were born from the location you were born at. Any house without one of the natal planets in it is considered an empty house.
When a house is empty, the energy manifests more purely (focused on the sign the house falls in), and it's believed you have less baggage and issues to work through. Houses with planets in them are seen as areas of life you still have to work on, while houses without planets in them are seen as areas you've already mastered (in past lives or early in this life) and are comfortable with. So instead of it being a bad thing, it's actually a good thing!
What is the 1st house?
The 1st house is the house of the self, and corresponds to your Ascendant or Rising sign (the sign on the horizon at the moment you were born and location you were born at). The 1st house is an important part of your personality, and shows how you come across.
Normally, any planets in this house would be a very important part of your life and personality, and may overshadow everything or have influence in virtually everything. But when you have no planets in the 1st house, it's entirely focused on the sign the 1st house falls in.
An Empty 1st House:
Some may worry that an empty 1st house means you have no personality, or struggle with showcasing yourself, but it's actually the reverse of that. When your 1st house is empty, this means you manifest the sign the 1st house falls in more purely in your life and personality. You have less to hold you back from doing that, and can express this sign in an easier way, without anything tinting it.
An empty 1st house can help you to showcase yourself more often, be more comfortable with attention, and more comfortable in your own skin. You can manage being around others, and present yourself well.
The 1st house links to new beginnings and journeys, so you may be someone who has an easier time starting anew, going down new journeys, and finding opportunities for new beginnings. You can make things happen for yourself, and may be more assertive and take initiative.
You may not be someone who needs to wait for something else to kick in before you can jumpstart things. Instead, you can do it yourself, and may be better able to make use of energy and enthusiasm for what you want.
You may be seen as a more natural leader, and can take the lead in a way that is comfortable for you. This may depend on the sign your 1st house is in though (or the sign may show in what part of your life you're a leader).
When it might be a challenge:
The Lunar Nodes (points in the Moon's orbit where the Moon crosses the ecliptic; are spiritual/karmic in nature) or Chiron (ruler of wounds and healing) in the 1st house may complicate things and make it so it's not as easy as if they're truly empty. The Lunar Nodes and Chiron aren't considered planets, so they're not factored in for the "empty house" designation (there are tens of thousands of asteroids, so technically speaking, no one has a truly empty house, but these bodies aren't factored in).
If your North Node is in the 1st house, you may struggle with manifesting your 1st house sign, especially earlier in life, and feel uncomfortable with the energy, with showcasing yourself, and with putting yourself out there. This is something you have to learn over time with age.
If your South Node is in the 1st house, you may be super comfortable with being out there and showcasing yourself, but you may also struggle with old baggage (past life or early life) and have to work on that, otherwise it weighs you down.
Chiron in your 1st house can make you more open about your wounds, and you may be someone who is seen as the victim or gets taken advantage of routinely. You have to work on healing, embracing the strength in healing yourself, and guard yourself better. You can take control of your healing and thrive.
If the 1st house cusp is anaretic (at 29 degrees), or if the 1st house ruler is anaretic. This might bring hurdles you need to overcome in order to showcase yourself, pursue what you want, and take more action.
The 1st house ruler intercepted (contained in another house), a singleton (only planet in an element, quality, or house type), conjunct Saturn, Uranus, Neptune, or Pluto (if not any of them), or part of a challenging aspect configuration (like the apex planet of a t-square) can also bring out some difficulties, but may not be as strong as the others.
Having these present may indicate challenges you have to deal with, but they can still be easier at times than if they were present with a different house that had a natal planet in it (especially if that planet is Saturn, Uranus, Neptune, or Pluto!).
Suggested Reading: Empty Houses in Astrology