I'm guessing you're veiwing that on a lowbie character. Lowbies get buffs to things like major brutality. Normally it's 20% but it can be different. That's why the number is bright white, like all numbers that vary. My level 3 shows 27% on major brutality.
Rally only heals when the effect ends. So it will heal if the buff timer runs out, or if you re-cast the buff. Your heal will be smaller if the effect ends by re-casting; larger if you let it go the full 20 seconds.