I think you need to be more specific.
What I assume is that the opponent had an A, and got an ace on the river (last card of the board), in that case, he had 3 outs, after the flop he had around 13% chances of hitting an A with 2 cards to come, after the turn he has around 7% chances of hitting an A with the last card.
If you want more details of
equity of the play, you should recall exact cards you had vs villain's.