There are many ways to calculate odds, that are used in different parts of the world. The most popular system is the American system, which is the one you'll see with + and - symbols before their numbers. Think of it like you're betting $100 - if you you find odds at -125, you'll have to bet $125 to get $100 in winnings on top of your money back. If you find odds at +125, your $100 bet will get you $125 on top of your money back if you win. So a +500 bet would give you $500 back on your $100 bet, plus your $100. A book that uses Decimal odds will instead give you 6.00 as your FIFA World Cup betting odds - essentially meaning that you'll have a 6x multiplier on your risk if you win. Same conclusion, just different ways to present them!