hang out on the street就是一个固定用法 ,就是逛街的意思?

是的.
固定短语：逛街；闲逛 hang out （on the street ）
例句：
They hang out on the street and go to the internet café.
他们就在街上乱逛,或者去网吧.

Our crew members do not want to hang out on the street, they want to be productive.
我们的成员不希望在街上闲逛,他们希望有所收获.

But, as a teenager, I had “better” things to do than hang out at the airport.
但是,作为一名十几岁的少年,我还有比在机场闲逛更“好”的事情要做.

You refuse to hang out with someone unless they make specific plans to hang out with you.
你不想和别人一起闲逛,除非他们已经制定好具体的计划,打算和你出去走走.