Icebreakers are activities that enable learners in a new group to start to get to know each other and for you to get to know them. They should relate to your subject in some way but the focus is on participation and talking to each other, not learning new material.
Many adult educators make use of icebreakers to find out more about their students. You could for example, ask them to share in pairs their previous experience and their reasons for coming to the course. Then ask students to feedback themselves, or on behalf of their partner.
There are many other icebreakers. You can find some in City Lit’s Teaching and Learning Issues (February 2018). A google search will result in many more.