What are some things to do with your 3 month old baby like I want to do things to help with his learning development

talk to her alot and read to her so she can see the pictures

What @kambam said but you can stimulate him as well. Like if he tries to sit up or roll over assist him. But stay in his view so he can see you. Singing, dancing and helping him with his hands as well.

Tummy time, toys, books, music games, going outside. He will learn things on his own when ready