Balloon
From Inkipedia, the Splatoon wiki
Balloons are game mechanics that appear in Splatoon's local 2-player mode, Battle Dojo, and in practice sessions before rounds of Turf War.
Appearance
Balloons appear in a variety of colors, tied to a weighted string that keeps them suspended in mid-air. In Battle Dojo, Balloons are decorated Battle Dojo's logo. Likewise, when found in Turf War, balloons are decorated with the Turf War logo.
Functionality
Balloons act as targets when testing weapons and Splatoon's controls. In Battle Dojo, each popped balloon awards players one point, until there is one minute left in the round, when they instead award two.