"There is one manager at the post office."

Translation: На пошті є один менеджер.

[ScottWilli909480]

Is it a rule to put the place /event first?

[sagitta145]

Yes. Place + є + X = There is + X + place. Other word orders are wrong, highly contextual or unnatural and confusing.

[human5421993989]

I wrote Є один менеджер на пошті ... i guess now i know why it was marked wrong

[hello20212021]

True