1.
early
At an early time.
2.
quickly, fast
At a rapid pace.
早く is the adverbial form of the i-adjective 早い. It covers three related meanings: early (time), quickly (speed), and soon (desire for something to happen).
Forms
早い → 早く (i-adjective → adverb by changing い to く)
Writing
- 速く: the standard spelling for speed of motion (速く走る, to run fast)
- 早く: for earliness and for urging ("hurry"): 早く起きる, 早く来て
The two overlap in the sense "quickly", and 早く is the far more common spelling overall.
Common expressions
Usage
早く! on its own works as an urging expression: "Hurry up!"