adverb
suddenly; abruptly; quickly; hastily
Most often describes something happening suddenly or unexpectedly. In some contexts it can also mean doing something quickly or hastily because the situation is urgent or at short notice.
空が急に暗くなった。
The sky suddenly grew dark.
急に作った資料なので、誤字があるかも
These materials were made in a hurry, so there may be typos.
adverb
steeply; sharply
Used for a slope, descent, curve, bend, or similar physical change becoming steep or sharp.
ここから坂が急に下っているので、足元に気をつけてください。
The slope descends steeply from here, so please watch your step.
道は橋の手前で急に右へ曲がっている。
The road bends sharply to the right before the bridge.