An RPA, or Role Playing Award, is given by the GMs when they see people interacting in character. It is meant to encourage people to not just grind skills. An RPA is not based on time, so don't worry that you need to run out and use it right away. Instead, for a certain number of points, you will receive additional skill gains, similar to the way training works. This stacks with training (additive, not multiplicative) and stacks with itself (in terms of the amount of points it is for). You can nominate other players for good roleplay and the staff may reward them and potentially you too.
When you obtain one, you will get a message for it and you can even get them while offline if you have to leave in a hurry for whatever reason.
You can see if you have one by typing effects.