Let’s quote some passages from Hoyle’s rules for the game of faro:
“The cards are shuffled and placed in a dealing box, from which they can be withdrawn only one at a time.
The dealer pulls out two cards, one at a time, the first card being laid aside, the one under it being placed close to the box; and the next one left showing.
The banker pays even money on all bets but the last turn. When only three cards remain, all different, they must come in one of six ways and the bank pays four for one if the player can call the turn.”
Thus, you see, if one can guess correctly, in the game of faro, how the last three cards will appear, or if one can guess correctly how any transaction or affair will develop, he “calls the turn.”