Imagine owning a home that could never truly be taken from you, no matter what. That's the unique privilege the Levites had with their houses.
In the system of ancient Israel, most property was tied to the land and the year of Jubilee. Land and houses in walled cities sold by regular Israelites had specific redemption timelines, with some houses becoming permanently theirs after a year if not redeemed.
However, Leviticus 25:32 makes a special provision for the Levites. The houses within the cities designated for them (these were cities where they lived and ministered, not just random possessions) had a perpetual right of redemption. This means a Levite could redeem a house they had sold at any time. It was never permanently out of reach, unlike other properties which might be lost forever after the Jubilee.
This reflects the special status of the Levites. They had no tribal inheritance of land in Canaan like the other tribes. Their role was to serve God and the people. Therefore, the houses in their cities were a fundamental part of their secure provision, ensuring they always had a place to dwell.