Albert Barnes Commentary Numbers 35:2

"Command the children of Israel, that they give unto the Levites of the inheritance of their possession cities to dwell in; and suburbs for the cities round about them shall ye give unto the Levites." — Numbers 35:2 (ASV)

Suburbs - Rather, “pasture-grounds,” required for their large cattle, for their sheep and goats, and for all their beasts whatever they might be (Numbers 35:3).