Let me start by giving examples
The square root of 25 is 5. How can I say it's 5?? Well when I multiply 5x5 I get 25
What's the square root of 121?? Again I know 11x11 = 121.
So now,can I define a square root? Yes,I can define the square root of a number N as a number which when multiplied by itself will give me back N.
You might want to try cubes as well.
Hint: Cube root of 8 is 2
27 is 3