雲

How it works

が (subject) marks 雲(くも) (cloud) as the thing doing the action. The verb is 流れる(ながれる) (to flow) in its て (te-form) form, joined to いく (go) — the pattern [verb te-form] + いく (go) shows motion continuing away from you, so it reads as “drifting off into the distance”. Plain register, no polite です (is) or ます (polite), so it feels like a quiet observation to yourself.