[AKQJ10]

First see the section on "Hidden outs".
If one opponent has, say, jacks and treys, you can beat that by catching a six or a queen on the river to make kings up. The board pairing counterfeits two pair by turning an overpair into a higher two pair.

However, if each opponents has a different two pair, then you don't have all those outs -- if one opponent has J3 and another has Q6, any river pairing the board will make someone a full house. If one has QJ and one has J3, then only a six or a king will make you a better hand.