Locations are offered on the Professional Plan to allow the owners and admins of those plans to separate the clients, admins and providers as needed. There are a variety of reasons why you might want to use a location.
For example, let's say your practice has two distinct brick and mortar offices and also sees online clients. You may, as a company, want to distinguish between which providers work at each location or between clients who are eligible for online are and those who may be only seen in the office.
There are lots of ways to use the location feature, the possibilities are only limited by your imagination.