Okay, imagine you live in a big house with lots of other people who also own their own parts of the house.
Now, because you are all living so close together, there are some things that you all have to follow so that everyone can be happy and safe.
Like, you have to keep your area tidy and clean, you have to be respectful to your neighbors and keep the noise down, and you have to follow certain rules that everyone agreed on.
That's what a homeowner association is! It's a group of all the people who own parts of the big house who have decided on rules that everyone needs to follow in order to keep the community nice and healthy.
So when you live in a house with a homeowner association, you might have to pay some extra money each month to help pay for things like keeping the lawns looking pretty or fixing broken things around the house.
But in exchange, you get to be part of a great group of people who all care about the same things as you!