Questions & Answers about Через час мы купим вкусные пирожные.
Why does the noun пирожные have an adjective ending?
Пирожные (pastries/cakes) is a substantivized adjective. This means it functions entirely as a noun in the sentence, but it declines exactly like an adjective. Because it is an inanimate direct object, it takes the plural accusative adjective ending -ые.
How do we know the gender of a word like пирожные?
Why are we using через to mean in an hour?
When talking about a future event that will happen "in" a certain amount of time, Russian uses the preposition через followed by the accusative case (here, час). It translates closer to "after an hour has passed." If you said в час, it would mean "at one o'clock."
Why use купим instead of будем покупать?
Купим is the future tense of the perfective verb купить. We use the perfective aspect here because the sentence focuses on the completed result of the action (successfully getting the pastries), rather than the ongoing process of shopping.