Tips?

Any tips on how to encourage my 18 month old to start talking? He speaks gibberish all the time and does some hand gestures such as pointing. He has said a few words before but never when I ask him to and lately he hasn’t said any at all he only does when he wants to which is not very often but is constantly talking gibberish like all day. He’s extremely smart and definitely understands like he knows how to brush his own teeth and wash his hands and when playing with toys he copies what I do but I really want to encourage him to start talking so If anyone has any advice I’d appreciate it!