If you decide to cash out a bet, your account will be credited with the figure displayed and the bet is terminated. If the bet goes on to win you do not receive any additional winnings and equally if the bet loses you do not have to give any money back. The amount being offered will change depending on the time remaining and the current outcome.
If you bet on Chelsea to win and they are 1-0 at half time, the offer you receive to cash out will change as the second half is nearing a conclusion. If your bet is losing you may be able to cash out less than your stake, more on that later.