6⁴ means "multiply 6 by 6 4 times"
Or
6·6·6·6
6^4 ("6 to the fourth power") is equivalent to 6 times 6 times 6 times 6; in other words, 6 is used as a factor four times.
Note that 6^4 = (6^2)^2 = 36^2. This hinges on the principle that (a^b)^c =a^(bc).
