f(x) is our regular graph where the y value is determined by the x value that is plugged in.
f(x + 2) = horizontal shift to the left 2 units
---x, the horizontal axis, is what is being altered here because the change occurs within the parenthesis. We always do the opposite action/move the opposite way when the shift occurs within the parenthesis.
f(x) + 2 = vertical shift up 2 units
---y, the horizontal axis, is what is being altered here because the change occurs outside the parenthesis. We move the function as we would expect to when the shift occurs outside the parenthesis.
Hope this helps!