Started the car yesterday and the check control came up with an alternating message :

CHECK BRAKE LIGHTS
CHECK PARK LIGHTS

On further investigation found the combined brake/park light in the right rear cluster was not working. In the owner's manual p.161 it is the light described by 5/2. Only problem is when it comes to giving details of what bulbs are needed it says

Tail light 2 : 21/5 Watt bulb
Other lights :21 Watt bulb

As this is both 5 and 2 combined what do I need to replace it ?

Sorry if this is a silly question but car mechanics are definitely not my strong point !!