The power (or exponent) of a number says how many times to use the number in a multiplication.
It is written as a small number to the right and above the base number.
In this example the little "2" says to use 8 two times in a multiplication:
82 = 8 × 8 = 64
But power can also mean the result of using an exponent, so in the previous example "64" is also called the power.
Another example: 24 = 2 × 2 × 2 × 2 = 16
We can say "2 to the power 4 is 16", or we can also say "the 4th power of 2 is 16"