" easy process"

My son Adrish. his mom call Adi. he stays 3+ seven months. he know 1 to 20 counting, writing A - Z, also write down bengali vowel. but can not colour recognizing. please help me the easy process.

Like all the rest you listed, practice. The boy will learn his colors, but everyone learns different things at different rates. Stick with working the basic colors - red, orange, yellow, green, blue, brown, purple, black - until he knows them. Get him crayons and coloring books. Say the colors when he uses them, get him to repeat them. He is not even 4 years old - he will learn. Have fun!