〜てくる: come and do; start to; has been doing

Shows an action coming toward the speaker, a change that has begun, or something that has gone on up to now.

Verb te-form + くる. 買ってくる (go buy and come back), 暗くなってきた (it has started to get dark), 慣れてきた (I have gotten used to it). Opposite of 〜ていく.