Since WiFi (most routers) is smart enough to not transmit if there's an ongoing transmission then it works. This is all I'll write here as to go any deeper is done in a classroom.
Since this means slower speed some may call that interference but it is actually cooperation.
In short they take turns speaking.
I am curious about one tricky question.
I have One Wireless Router and it works fine my two laptop is connected with it now I bought another wireless router and place near the first one and connected my third laptop with new router.
Let’s say these router are working on free band which Is 2.4 GHz and both are working on same router so why their frequency not interfere each other although my devices are properly connected with their respective AP.