When everyone else passes, the person who was the last to bid 'takes the bid.' The player then declares one suit to be trump. Once the bid reaches 60, ever bid thereafter must be increased by 5.
If the bidding continues long enough, or if a player feels confident about the playability of his/her hand, he/she can bid 60 right away. The number the bid is increased by times ten signifies the number of points in the player's hand. When a person increases a bid my a number other than one, the player is letting his/her partner know how many points he/she has in his/her hand. This will become important when the hand is to be played, since having aces usuall guaruntees points will be pulled.
If the first person to bid declares 51, he/she is signaling to his/her partner that he/she has an ace in every suit. Other types of bids include simply increasing the bid by one, increasing the bid to signal your partner how points you have in your hand, and bidding 51 right away. In order for a person to declare trump, there must be a marriage for the person to declare trump in. A player may choose to not bid if they don't have a strong playing hand or don't have a marriage. Bidding is the act of declaring a number that you think you and your partner can make between your melds and the ability to pull points during tricks. After the cards have been dealt, the player to the left of the dealer begins the bidding.