Outreach is an activity of providing services to any population who might not otherwise have access to those services.  A key component of outreach is that the group providing it not be stationary, but mobile; in other words they are meeting those in need of outreach services at the locations where those in need are.  In addition to delivering services, outreach has an educational role, raising the awareness of existing services.
In this case, those services revolve around the arts.