Lenny: So Mayra got a new place.
Bruce: Really? Where is it?
Lenny: Over on 4th, kind of near the freeway.
Bruce: Isn't that kind of a bad neighborhood?
Lenny: Yeah, but she's street smart. She grew up in an area like that, so she knows how to survive. And she's saving a ton of money compared to her last place.
Meaning: The expression street smart means that someone knows how to survive in dangerous urban areas, usually because they have experience living in similar areas. The expression can be used as an adjective, as in the example above, or as the non-count noun street smarts, as in the next example:
Don't go into that neighborhood without any
street smarts; it can be a rough area, and
people walk around with expensive jewelry and talking on expensive mobile phones are likely to get mugged.