A bookmaker - this is a firm which organizes the sports betting. It defines the rules of the game, maintains a list of sports events, takes bets and pays out.
A bet - this is the sum which the punter places on a specific outcome of an event. After the event finishes the bets are decided upon the results of the event. The sums from the bets of the losing punters are for the bookmaker and the winners receive the winnings.
Odds - this is the quantity used for defining the winnings the bookmaker has to pay out. With some bookmakers it is called “price”.
Line - this is a quantity used for defining the possible outcomes of an event including the odds for the winnings.