If I pick wrong the round is over for our team. If I pick at least one of the right ones and no wrong ones, we keep playing. You might say 'Frost, 2' and hope I pick Snow and Tundra, but not Russia.
The point of Codenames is simple: You say a clue word, and how many of the words on the board that clue word relates to, in order to get me to pick particular words. Codenames is a brilliantly fun word game for nearly anyone.