Joshua 21:30 lists two towns, Mishal and Abdon, along with their surrounding lands, as being given from the tribe of Asher. These towns and their "suburbs" were set aside for the Levites, who were the priestly tribe in Israel.
In context, this verse is part of a larger section where Joshua and the leaders of Israel are distributing towns to the Levites from the territories of the other tribes. The word "suburbs" here refers to the pasturelands around each town, which provided space for the Levites’ livestock and daily needs. This arrangement helped ensure the Levites were spread throughout Israel, serving the people in various regions.