Here is another take. The > and < arrows indicate focus has not been achieved. If you were to manually turn the focus ring, the arrows show the way the top of the focus ring should be rotated.
> means, you rotate the ring clockwise, viewed from the shooters position. < means focus will be achieve if you rotate the ring counterclockwise.
The instant focus is achieved, the green light comes on. The arrows disappear simultaneously.
When using autofocus, the green light means that focus was achieved.
There are two mechanism controlling this, one when you are looking through the viewfinder. The other, when you have Live View turned on. One senses light phase, and one detects contrast. Whichever method, you have a fast lens and so the additional light coming through the lens means AF will be very fast. Dim light makes focus more difficult.