I have a 5 year old son can't speak clearly.. I noticed it since he was like 2 years old.. what should I do? He can speak only 2 words but sometimes bot clear.. please help

Where do you live?
Does he have siblings? Is he in preschool or daycare?
Do you speak another language in an English speaking country?

Ordinarily by now he might have had his hearing tested, his mouth and throat examined for any physical abnormalities, and been seen by someone in a speech therapy field.
It doesn't mean there is actually anything wrong. Many fine intelligent successful adults were very slow to start talking.
But if for instance he's partially deaf, the sooner you find out the better.