! means factorial, if you did not already know. It means multiply together all the numbers leading up to that number. For example, 4! = 4x3x2x1 = 24
Evaluate means just solve it.
9! = 9x8x7x6x5x4x3x2x1 = 362880
5! = 5x4x3x2x1 = 120
362880 - 120 = 362760
There is your answer