If you have not yet tried Squares and Cubes do this first.
A square root is the opposite of squaring a number. The symbol for square root is √.
So if 3²=9 then √9=3
A cube root is the opposite of cubing a number. The symbol for cube root is ³ √.
So if 3³=27 then ³ √27=3
TrySquares, Square Roots, Cubes and Cube Roots to help you become familiar with the important examples of this.