I'am searching for an add-on which put inside each button, an average mount of DPS or HPS.

for example =

i.e = into a arcane shot button, i saw 1550, which is the average damage dealt by this spell

same for priest or druid spells = an amount of heal done is inside the button.

rejuvenation = 880 i.e

can someone help me ?

you can see in this interface =>>

Try DrDamage or Theorycraft.