How do you stop a character from passing through a wall?

Hi! I am very new from Unity, and I made a cube into a wall. I made a building and I don’t want the character exploring the building to pass the walls, I want them to bump them but not pass it. Do you have any ideas that are simple for me to use and understand? Because I am new, I would like to use an easier way to do this. Please help! Thanks.

To do this you need a collider.

Box collider - A rectangle / square based collider than you can put on each one of your walls.

Mesh collider - If you have imported a model then you can apply this so all the colliders are created for you.

Make sure that on both colliders you have unchecked ‘Is Trigger’ as this will create the collider and allow you to still pass through it.

Hope this helps.