The incident in question took place during the Indian innings, when, according to an ICC statement, Pollard "called a substitute onto the field despite having been repeatedly told by the umpires that a request must be made for a substitute to come onto the field and being advised to wait until the end of the next over" and he "failed to follow the umpire's instructions".
After being charged by Nigel Duguid and Gregory Brathwaite, the on-field umpires, third umpire Leslie Reifer and fourth official Patrick Gustard, Pollard denied his guilt in the matter and that necessitated a formal hearing with match referee Jeff Crowe, who found him guilty and handed out the penalties.
Pollard didn't bowl in the match and scored a run-a-ball 8 not out as West Indies got to 98 for 4 in 15.3 overs after India had put up 167 for 5, which meant a 22-run win for the visitors on the DLS method, giving India the three-match series 2-0 with one game left to play.
Pollard did have a better outing in the first game of the series in Florida - his first game for West Indies since November 2018 - where he scored 49 in 49 balls in a poor West Indies batting effort of 95 for 9.
The third and final match of the series will be played at Providence Stadium in Guyana later today.