So for these questions, it's basically asking what would f(3) equal when the x-value of 3 is plugged into the function f(x). Since they give you a table here, simply go the x-value 3 and look at what is the number given on the right of 3. That is your y-value which is what this question is looking for.
Examples:
What is f(2)? (Go to the x-value 2 and look at the right side number. It would be 6.)
What is f(-1)? (Go to the x-value -1 and look at the right side number. It would be -3.)
For this problem, what is f(3) then? (Go to the x-value 3 and look at the right side number. It would be 9.)
Hope this helps!