If the area of a square is `36" m"^(2)`, then its side is 6 m long.

Answer

To find the side length of a square when the area is given, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the formula for the area of a square**:
The area \( A \) of a square is calculated using the formula:
\[ A = \text{side}^2 \]
where "side" is the length of one side of the square.

2. **Set up the equation using the given area**:
We know from the problem that the area \( A \) is \( 36 \, m^2 \). Therefore, we can write:
\[ \text{side}^2 = 36 \]

3. **Solve for the side length**:
To find the side length, we need to take the square root of both sides of the equation:
\[ \text{side} = \sqrt{36} \]

4. **Calculate the square root**:
We know that the square root of \( 36 \) is \( 6 \):
\[ \text{side} = 6 \, m \]

5. **Conclusion**:
Thus, the length of each side of the square is \( 6 \, m \).

### Summary:
The side length of the square is \( 6 \, m \).