RF modules have many uses and are used in almost all electronic devices with RF.
For example: the radio frequency module of the mobile phone, the radio frequency module of the GPS receiver for navigation, the tuner of the TV (also a form of the radio frequency module).
The function of the radio frequency module is to convert radio signals into wired electrical signals, or vice versa. Why do we separate wired electrical signals from radio signals? Because of the particularity of radio signals, the signal is weak, and the interference is very strong.
In the circuit, we usually separate them from the general circuit, and separate all aspects, such as power supply, ground wire, space and so on.