Walk is a verb. I walked there. She is walking over here. He can walk better now Etc To go for a walk is a phrase. I'm going to go for a walk: I'm heading out to have a stroll, a wander around, clear my head, that sort of thing. It means to walk for pleasure rather than a purpose (I.e. walk because you want to walk, not because you have to get somewhere).

“Go for a walk”means a pleasure activity that we enjoy. “Walk” is just one way of getting from A toB. “ I will walk to the supermarket “ For example.