Just in case it's not obvious, it's tempo/timing. The top is similar to the FG kick window you'd be used to from football games, but instead of wide left, left, middle, right, wide right, you have very fast, fast, perfect, slow, very slow.
But... you don't have to use the in game set timing. You can go into the menus and calibrate your swing. So if you are a naturally fast or naturally slow swinger, you can adjust it to fit your style.