Turnover is the total bet amount either win or loss.
For example:
Your first bet is 10PHP, but loss 8PHP;
second bet is 20PHP, and win 1000PHP;
third bet is 50PHP, and loss 50PHP;
your total turnover is 80PHP (10+20+50).
Here is an example, you need to use bonus 98PHP to reach 25 times turnovers to pass the promotion. It means that you have to reach 98 x 25 = 2,450PHP to pass.
However, please note that each promotion has different turnover rules. Sometimes it has different way to calculate the amounts.