Good at handling real life in a city, especially the rough parts of it — knowing which streets to avoid at night, spotting a scam before you fall for it, reading people quickly, staying safe and getting what you need without much money or protection. It is a compliment, and a warm one. Someone street-smart may have very little education, and the word is often used to say exactly that: this person did not learn it from books, they learned it from living. English likes to set the two side by side — "he's not book-smart, but he's street-smart" — and in that pair the street kind is usually the one the speaker admires. It came from American English and is now used everywhere, mostly in speech and in casual writing. "Streetwise" means the same thing and is more common in British English. As a describing word it can sit before the noun (a street-smart kid) or after "is" (she's very street-smart). The noun is "street smarts", written as two words with no hyphen: "he's got street smarts".