1, Clockwise is the way hands move on a clock, counter-clockwise is the opposite direction.
The arrow in the picture is pointing in the opposite direction from how a clock moves, so it’s a counter-clockwise rotation.
2. For the number of degrees, you start with the fact that a full circle is 360º. This rotation is a quarter of a full rotation, so it’s 1/4 of 360º.
360º÷4 = 90º
Another way to also look at this is as a clock. The triangle started at 6 o’clock and moved to 3 o’clock. It went back in time (counter clockwise) by 3 hours. Since there are 12 hours on a full clock, the 3 hours is 3/12 or 1/4 of the clock. It’s the same answer, just a different way to look at it.