How to make one side of the wall transparent (Not both sides)

Hello, I have seen maps where one side is a wall and the other side is transparent like glass. How do I acheive this?

I would not know how to do this on Fortnite Props, but if you’re going for custom props you can just check Two-Sided checkbox inside the material

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Then you can use the Two Sided Sign node to do achieve different results in your material, for example :

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