As a value, according to which you can choose between the options over/under.
In most cases this value is 2.5, however, there are games for which a bigger number is expected, so the value can reach 3.5 or higher.
Example of Over 2,5 Goals:
3 or more goals must be scored in the match in order to win
Example of Under 2,5 Goals:
2 or less goals must be scored in the match in order to win