RC6107 10AX 250V~ BS 3 gang 1 way switch
3 gang 1 way light switch
This format of light switch has three discreet switches on a single face plate. Basically this is three Single gang 1 way switches on a single face plate.
The only place you would use such a beast is if you had three lights (or sets of lights) in a single room each controlled by one of the single switches. This arrangement is not common, you are most likely to find a 3 gang 2 way switch used (this will do the same job but you will have spare L2 terminals on each gang that you would not need to use).
Each of the gangs (of which there are three) work like this: when the switch is ‘on’ the COM and L1 terminals are connected together. When ‘off’ the COM is connected to nothing.