Common English Expression

👉To hang out

If someone asks you

where you usually hang out, they want to know in which place you prefer to be when you have free time. And if your friends ask you if you want to hang out with them, they’re asking you if you’re free and want to spend some time together.
And what about if you ask your friends what they’re doing and they just answer “hanging out”?
It means that they are free and not doing anything special.