The description says the game comes with 55 cards. However, there are only 20 "game" cards. The others are just for people to write their answers on, and to keep score. Compared to the main game which comes with 500 cards, this really is just a small taste of the main game.
Been years since I originally played this where it was a game of just defining words. Now, there are 5 categories so a card looks like this :
Events : Eight people were left injured in a Montenegro cafe when...
Words : Nares
Laws : In the state of Alabama, it is illegal to wear a fake...
Initials : B.C.C.C.A.
People : Reuben H Donnelly
Players take it in turn to be the "Dasher", who rolls the die to see which category will be played in the next round. (S)he then reads out the category question (example is above). The other players (try to!) either finish off the sentence, or define the word/initials/person - they write this on a card which they hand to the Dasher. The Dasher then reads out the definitions which were written down including the real definition which is printed on the back of the Balderdash card. Each player then says which they believe is the real definition and points are awarded to each player based on whether they were correct, or if someone else chose their definition.
It's a good game, you'll probably want the full sized version 20th Anniversary Absolute Balderdash
which also has a box and lots more cards.