Bet 10 Get 20 means that when you sign up with a betting site and place a qualifying bet of £10, you will receive £20 in free sports bets. These free bets are credited to your account after your initial bet settles, and you can use them on various sports markets. For example, if you place a £10 bet on a football match, you will receive £20 in free bets after the bet settles. This Match.Center page provides more information on Bet 10 Get 20 offers and how they work.