The square root of a number is a number that when you multiply it by itself you get back to your number.
Example:
What is the square root of 16? You are looking for a number that when you multiply it by itself, you get 16. Try 4. 4 multiplied by itself is 4 * 4 and 4 * 4 is 16, so 4 is a square root if 16. There is another square root of 16. It is -4 since (-4) * (-4) = 16.
What is the square root of 4? 2 and -2 since 2 * 2 = 4 and (-2) * (-2) = 4.
You can think of it in terms of squares. The area of a square is 36 say. The square root in that case is the side length.
Draw yourself a square. Label one side 6. Find the area. The formula is side length times side length. 6 * 6 = 36
The root of the square is 6. I suspect your problem is more language that math. The length of the side is the square root of the area of the square.
Every square root can be thought of that way. For example the square root of 200 = 14.14
Draw a square. Label one side as 14.14. That means that square has an area of 200 units. It has a side length of 14.14. That's the square root of the area.
If you're still stuck leave a note and we'll try something else. Do you know how to find square roots on your calculator?