A moneyline bet is the simplest wager: you pick which team or player wins. There is no point spread, so the odds carry all the information about who is favoured.
American odds use a plus or minus number. A minus number, such as -150, tells you how much you need to stake to win $100: here, $150. A plus number, such as +130, tells you how much you win on a $100 stake: here, $130. The favourite always has the minus number.
To convert odds to a break-even probability, use 100 / (odds + 100) for plus odds and odds / (odds + 100) for minus odds (ignoring the sign). At -150 the sportsbook implies about 60 percent; at +130 about 43 percent. The two sides add up to more than 100 percent, and that gap is the sportsbook's margin.
Source: Playfield Review explainer, based on standard sportsbook pricing conventions.