That symbol is square root.

The square root of a numer is what one number multiplied by itself equals that number

Like

The square root of 4 is 2, because 2*2=4

Get it?

√ = square root.

Happy, thanks for you answer :)

You would have been better to use a different example.    

people get confused about 2 becaue 2+2=2*2

A lot of people think 5^2=10 not 25 because they confuse the times with a power.

Fine!  How about 16?

4*4=16

Is that better Melody?

Square Root of 16 is 4

Yes that is better - thanks Happy