Pls explain if u have something in ur mind

I have a male coworker start to be friends with me and open up to me
What's that means? Is he interested? How can I know?

He social but when go one to one he is very specific and have small circle and I'm in this circle but in the same time when our female collague ( she is talkative, beautiful) with us for coffee or something his body language go around her a lot
Idk confusing