What do you mean by functional dependancy in dbms?

Dependency means that the one entity dependents on another entity. This is also applicable for the Function also.

For Example : If you trying to check the general function which tells you about the rooms availability, which consist of checkFreeRooms() and we can have the checkForACRooms() and CheckForSuits(), So the general function for checking Rooms dependents on the other rooms as above