What is the definition of urban land use?

Urban means city. So urban land use means something related to how land is used in a city.

You may be referring to zoning laws; in that case, there are several (possibly dozens) of different zones in your city. Some land is zoned for residential use (where we live) and some for commercial or industrial use (where we work).

Outside of the city, there will be areas zoned for agricultural use, for farms and such.