How to fix a fairly big hole in the wall?

photo? what is the wall made of? plasterboard? plaster over screen? plaster and lath? brick? stone? concrete block? "aluminum" siding?

each requires appropriate materials and methods, but you give us nothing to go on.

take photo of the damage with your phone and go down to the loacl hardware or home improvement -- show the problem to the sales staff and ask advice from them. they'll tell you/show you what materials you need and either tell you or point you to YouTube on how to do the task

Fix wall big hole.

Depends on what the wall is made from.

Hang a picture over it. Problem solved