What does 8 to the power of y means?

8^8 is the amount of possible combinations Vriska’s Dice has, which is 16777216 possible dice rolls. y is a letter used in maths to define an unknown number. y=8, as he explains later on, but it’s basically used merely for a SBaHJ joke, as 8^y is the emote way of writing Sweet Bro’s face.