IEEE 802.11f is a set of rules created by a group of really smart people to make different kinds of devices that use Wi-Fi better at talking to each other.
Think about it like this: you have a bunch of toys that all need to be taken care of, but they don't all speak the same language. So, you get a bunch of adults together who know lots of different languages and teach them how to communicate with each other so they can all take care of the toys together.
In the same way, IEEE 802.11f helps all the different kinds of devices that use Wi-Fi to talk to each other better and work together. This makes it easier for you to use your Wi-Fi devices without any problems.