1. To begin doing some task It's already 6:00, so I better get started on dinner. Have you even gotten started on your homework?

2. To cause someone to start enthusiastically discussing some topic. In this usage, a noun or pronoun is used between "get" and "started." Don't get Grandpa started on the weather unless you want to hear about the Farmers' Almanac all night. All right, who got Uncle Fred started on tax reform?