in a heartbeat

in a heartbeat  당장, 바로, 재빨리

"to do something in a hearbeat" means to do something very quickly,instantly right away, now. "do it in a heartbeat" usually we use this expression like this  'If I would ~~~ in a hearbeat.' The nuance is 'If I had the chance to do something, I would do it now, immediately.'

 A: I hate my job.

B: Google's hiring.

A: Oh, I'd take a job there in a heartbeat.

B: Yeah, but would they take you?

A: 내 직장 정말 싫다.

B: 구글에서 채용하고있데.

A: 오, 당장 거기서 일하고 싶은데.

B: 그치, 그런데 구글에서 너를 채용할까?