Ask him what his favorite things are (pick one topic - hobby, place, car, whatever he seems like he kind of likes) and ask him to tell you about it/why he likes it. People generally love to talk about things they love. Hopefully you like it/understand the interest. And actually listen and stay engaged. Ask questions about things he's vague on.

Conversations are two way streets. Hopefully you also find an intersection of interests yoy both like and then you can both dive into