The term 5-bet refers to the third re-raise in a betting round, usually seen preflop. For example, suppose you raise to $10 preflop with $1/$2 blinds. If a player re-raises, that's a 3-bet. If you re-raise again, that's a 4-bet. If a player re-raises again, that's a 5-bet.
Five-card draw (also known as Cantrell draw) is a poker variant that is considered the simplest variant of poker, and is the basis for video poker. As a result, it is often the first variant learned by new players. It is commonly played in home games but rarely played in casino and tournament play.