My son is 2 yrs and 3 months Old. He can only speak 3 - 4 words like Mama, Baba, Bama, Yea.?

Try finding something he is REALLY interested in. Then tell everyone who looks after him what it is called. So that they all call it the same thing. Like his teddy for example. And get everyone to concentrate on the word for it. E.g say Teddy everytime you hold it, move it, give it to him. I've noticed my daughter knows far far more words than she says. If I say "where is Tigger" she looks for tigger and brings him to me, but when she wants tigger given to her she just points and says "BUP". Bless her. One day he will walk up to you and say a full sentence and you'll be amazed! If he picks up vibes from you that there is something wrong to do with talking, it could hold him back. He doesnt sound like he has any hearing or cognitive issues if he looks at you when you talk and communicates with gestures. He's just late with it!

he sounds pretty normal. some kids just take a while to express themselves vocally. Most children don't really talk "plainly" till they are closer to 3, in my experience. Try books with pictures of things he may recognize (like balls, trees, ect.) and practice with him some everyday. Keep talking to him, even singing to him and try reading to him, if he'll let you, pointing out different things in pictures to him. Don't be pushy, just subtly encourage him and just give him time. If you feel very concerned, speak to his pediatrician and see what he/she says about it.