Every object you create on the layout has a collision box, you can edit the size and shape of the collision box of the sprite objects.
You use collisions to trigger events. Enemy on collision with player triggers damage.. or anything like that.
Try reading the manual:
i didnt succes to do it. if its not clear i just want the player object wont pass through the wall object. (in top down shooter game)
for example if i have 2 sprites: player , wall
i wrote in the event sheet: player- on collition with another object (i chose wall) - add collitions enbaled
and it didnt work.
so i wrote in the event sheet : when start of liyout set player solid behaviour enbaled
and when start of layout set wall solid behaviour enbaled
and it didnt work too.