psv=* is an access key. psv=yes means taxi's and busses are allowed to drive on this road, however it's not needed since by default we assume highway=primary is access=yes, ie. anyone can access it, cars, busses, bicycles, motorbikes.

The tag doesn't indicate the road segment is part of a bus route, the bus route relation at https://www.openstreetmap.org/relation/2733626 indicates that.

https://wiki.openstreetmap.org/wiki/Key:psv