、。
I checked the clock — exactly 9 PM.
Literal
Clock [object-を] confirm [when-と], 21-[hour] exactly.
体言止め (noun-ending) at the end: the final clause 21時ジャスト is a bare noun phrase with no copula — a crisp, clipped narrative style. ジャスト is wasei-eigo for 'exactly, on the dot' (e.g. 5時ジャスト 'exactly 5'). 21時 uses the 24-hour format, standard in written Japanese for precision. ~と here is the automatic conditional — 'when X, then Y (naturally/automatically).'