The square root of 25 is ±5 (or 5 and -5).
The square root of a number is the number that when multiplied itself makes the number. In other words, when the square root of a number is taken to the second power, it would make 25 (at least in this case). The easiest answer would be to say that the answer is 5 (since 5² or 5 * 5 is equal to 25). But, if you were to 'dig deeper,' you would see that (-5)² or -5 * -5 is also equal to 25 (since an even number of negative signs cancel each other out). Therefore, the square root of 25 is ±5.