It is a loop. It will perform the actions within that loop the number of times specified from A to B. In the example you posted, it is 1 to 10, so it will execute the actions within that loop from 1 to 10. (1, 2, 3, 4.... 8, 9, 10 end. 10 times)
As greenwhy posted, the numbers you input for the "x to y" part can be used within the loop if you want to do something for different players. If you use his example, it will set the gold of Player((Integer A)) to 120. Since it is within the loop, "Integer A" represents the current number it is on. Since it is from 1 to 6, it will perform that action 6 times, and in this case, it will set each player's gold (player 1 to player 6) to 120.