Don't know where you are but in Texas, they're just used for decoration and don't mean anything. The Pennsylvania Dutch used to hang hex signs, sometimes stars, sometimes circles, on their barns to ward off evil.

Stars have long been a design of preference, even when they're not any particular meaning. You will see a lot of suns, too. In the 1970s stars and moons were everywhere. I just bought a house in January, and after hacking down what was nearly a jungle, I found a huge star on one fence and a big crescent moon on another.
In Texas, they are part of the state flag, so they are all over there. Bottom line: people love them.

It's a country thing. It doesn't have any meaning just decoration.

Besides some people using them for simple decoration, they may also signify that a family member is serving in the armed forces (blue star) or has died in the line of duty (gold star). The number of stars tells how many family members are serving or deceased.
This tradition started in WW II with white flags and stars on them.