Zoning is the system a city government uses to decide what may be built where. The planners draw a map, cut the city into areas — zones — and give each area a rule: this area is for houses only, that one for shops, that one for factories, this one for parks. If you own land, you may only build what the zoning for your area allows. It is why a steel factory does not appear next to a primary school, and why a quiet street of homes stays quiet.

The word is a noun, usually uncountable, and it often works in front of another noun: zoning laws, zoning rules, zoning regulations, a zoning change, a zoning board. You will hear it constantly in news stories about housing, rent, and city building — especially American news, where zoning fights are a big political subject. People argue about it because zoning decides how many homes can exist, and that decides what rent costs.

The verb behind it is 'to zone', and you will very often meet the past participle form: 'this land is zoned for housing', 'the area was rezoned last year'. That is probably the most common way ordinary people use the idea.

One honest note. This is very much a Western, especially American, way of talking about city planning. Taiwan does the same kind of thing under different names, so the English word does not map onto one single Chinese term perfectly — 都市計畫 covers the whole planning process, while 土地使用分區 is the closer match for zoning itself.