There are many different types of walls: garden walls, mental walls, etc, but do they all help to protect us physically and/or mentally? Answer: yes and no.
For example mental walls. Mental walls are there to mentally block us from doing something, in some cases this can protect us from doing the wrong thing. However, they can also prevent us from trying something new, like a new sport or an activity. As well as this, they can make us close ourselves of from the rest of the world. Like most things, they can be good and bad.
Another example is physical walls ( garden walls, fences, brick walls). These type of walls are usually used to keep people out and protect you and your property, or mabye even to just look nice. There are other physical walls like The Great Wall of China which was built to keep China safe, but is now a tourist attraction. Donald's Trump plan is to build a wall that divides Mexico and America, so that people living in Mexico can't get into America ( as you should know by now!). This wall is unnecessary as it only causes a hinder to the people of Mexico looking for a brighter future.
To conclude I believe that if used for the right purpose, walls can keep people safe, but if used for the wrong reason they can have a bad effect on people.