The Battle Bundle was a Battle Pass Mechanic in Fortnite.
It was introduced at the start of Season 2, with players having the option to buy it with 2,800 V-Bucks (The equivalent to a $19.99 Fortnite V-Buck Card and £15.99 Fortnite V-Buck Card). This would make players automatically get 25 levels at the start of a season, making it quicker to finish the Battle Pass. The Bundle was a popular feature, as many players would buy it because it was really hard to level up, especially during Chapter 1.
The battle bundle remained until Chapter 2: Season 4 and was replaced by a bundle of 25 levels, available for 1,800 V-Bucks.