Breakdown of Через час кое-кто сделает нам сюрприз.
мы
we
час
hour
сделать
to do (perfective) / to make (perfective)
через
in (after a period of time)
Questions & Answers about Через час кое-кто сделает нам сюрприз.
Why use кое-кто here instead of кто-то?
The prefix кое- means the speaker knows exactly who the person is, but is keeping it a secret from the listener. This makes it the perfect word for teasing a surprise! If you used кто-то, it would mean "some random person (and I have no idea who it is)".
The English translation says "will give us a surprise," but doesn't сделает mean "will make" or "will do"?
Exactly! In Russian, you "make" a surprise (сделать сюрприз). This is a set phrase, so you shouldn't try to translate the English verb "give" literally here.
I thought в meant "in". Why use через for "in an hour"?
When you are talking about an action that will happen after a specific amount of time has passed (like "in an hour" or "in five minutes"), Russian uses через followed by the accusative case. В is used for "in" when talking about locations or specific days, months, and years.
Why is it сделает and not будет делать?
Сделает is the future tense of the perfective verb сделать. It focuses on the completion of the action (the surprise will be successfully delivered). Будет делать is imperfective and would focus on the ongoing process, meaning "will be making", which doesn't fit the sudden nature of a surprise.