Solitaria is the game where you need to find the card which does not match any of the other cards.
This game requires logical thinking. I would recommend that you practice first using Learning Mode.
For example, one card might be the only one with four sided symbols on it, while the others are of circles.
You have to look for the systematic difference – whether it be colour, the shape of the symbols, or the arrangement of the symbols.
One card will always stand out from the rest, and you need to find this card.