"Anti-football" is a style of football that relies only on passing and an extremely defensive, aggressive, physical, robust style of play of football where one team deploys their whole team, except the striker, behind the ball. In doing so, they try their best to stop the opposition from scoring, rather than trying to win the game themselves. It is also used to criticise the playing style of teams who prevent the game from moving on with actions such as: kicking the ball forward without trying to reach any players, intentionally diving and stopping the play for several minutes or kicking the ball away when a free-kick is awarded, to waste time (usually penalised with a yellow card if too flagrant).
On the other hand UEFA has a prize of fair play for teams of which is part the avoidance of anti-football. If players pass try to "unlock" the game, play offensively, take risks, do retain possession. It increases their fairplay note (along with avoidance of fouls, and respect shown by fans). The 3 best rated teams of europe could be automatically qualified in Europa league and were (and still are) given a monetary prize.