Find the word definition

Wiktionary
away goals rule

n. (context sports English) A rule whereby, in case of an aggregate draw, the team with the most away goals wins.

Wikipedia
Away goals rule

The away goals rule is a method of breaking ties in association football and other sports when teams play each other twice, once at each team's home ground. By the away goals rule, the team that has scored more goals " away from home" will win if scores are otherwise equal.

The away goals rule is most often invoked in two-leg fixtures, where the initial result is determined by the aggregate score — i.e. the scores of both games are added together. In many competitions, the away goals rule is the first tie-breaker in such cases, with a penalty shootout as the second tie-breaker if each team has scored the same number of away goals. Rules vary as to whether the away goals rule applies only to the end of normal time of the second leg, or applies in extra time as well. It was first introduced by UEFA in 1965.