Gear — mechanical gears, transmission gears in cars or bicycles, and figuratively equipment or settings (e.g., in games).
急な坂では低いギアに入れて登ると楽だ。
On a steep hill it's easier to climb in a low gear.
古い機械の歯車（ギア）が摩耗して交換が必要だ。
The gears of the old machine are worn and need replacement.
ゲームで強いギアを手に入れてキャラクターが強くなった。
I got strong gear in the game and my character became more powerful.