I have no idea what the heck evaluate means

Evaluate basically just means to solve.
Replace the given vaule of m into the equation to get -8/2.
Then solve.
-8 divided by 2 is -4
Here is your equation:
[tex]\frac{m}{2}[/tex]
In the question, you are given that m is equal to -8. Substitute m with -8. Here is your new equation:
[tex]\frac{-8}{2}[/tex]
Now, all you need to do is divide. Remember:
In this question, you're dividing a negative number by a positive. That means the answer will be negative. Divide:
[tex]-8 \div 2 = -4[/tex]
Your answer is -4.
If you have any questions, feel free to ask in the comments! :)