The moment a team wins the ball back and can attack immediately, before the opposition has a chance to reorganise. Fast attacking transitions can cause chaos, catching teams with players out of position who were just on the attack themselves. Some teams build their entire DNA and game tactics around winning the ball back and attacking quickly.
Andoni Iraola's Bournemouth have been a breath of fresh air in the Premier League, specialising in high-pressing turnovers that lead to fast attacking transitions. Utilising the pace of attackers like Rayan (and Semenyo before he signed for Manchester City), his teams are always one of the most effective in fast breakaways leading to chances on goal.
When Ashley Young was asked about Sir Alex Ferguson in interviews, he'd often refer to him as "the gaffer" - a term of respect for the man who controlled every aspect of United's dressing room for 26 years. Even former players still call him "the gaffer".