Yes, there is good bus service in Corozal. You can catch a bus from Corozal Town to Belize City, Orange Walk, Belmopan, and other places that connects to Corozal. There is also a bus service that you can take all the way to Mexico. You can take buses to Chetumal, Mexico, the Free Zone, etc.
Within Corozal, there are no bus services but you can take a taxi. Corozal is a pretty small town of only about 2 miles so you could almost walk to wherever you want to go within Corozal.
(Vintage bus in Belize, pictured.)