It means do Ri Di R D (with R being Right face clockwise and Ri meaning anticlockwise) several times.
Line up a corner that needs rotating in the front top right corner position, then do the alg either 2 or 4 times until it fixes its rotation. Then rotate the next top corner to fix into that position and repeat until all are fixed.
The algorithm will need to be done 0, 6 or 12 times in total. The cube may appear messed up after you've fixed a corner. Don't worry. The cube returns to a nearly solved state every time you do the alg 6 times, so you might need to do it twice on one corner and 4 times on another before you see the nearly fixed state you remember.
Please take off topic discussion off this forum. Thanks.