An ignition advancer does exactly what it says on the tin - it advances the ignition timing. This usually boosts low end and mid range power and smooths it out a bit. You're also supposed to get sharper throttle response.
It tends to boost partial throttle opening power. That's why the effects aren't always clear from a dyno run (full throttle, blast the nuts of your bike type situation).
I believe that there are two types available for the R6. A standard +4 degree ignition advancer and a fancy variable advancer that needs to be tuned. +4 might be a tad too much for this bike.
Also, they have been know to actually lower the peak power and obviously, huge advances can damage the engine.