O believers! Remember the favor of Allah, which he bestowed on you, when you were attacked by your enemy’s army (during the battle of Trench/Confederates) and We unleashed against them violent winds and invisible forces. Allah saw all that you were doing.
Meaning:-
Bestowed: to present as a gift, an honor
The Battle of the Trench: also known as the Battle of the Confederates. (January/February 627 A.D.) was a 27-day long siege of Yathrib (now Medina) by Arab and Jewish tribes. Failure of siege; Decisive Muslim victory led by prophet Muhammad.
Confederate: united in a league, alliance, or conspiracy. a person, group, nation, etc.,