Breakdown of Ты купил что-нибудь из ягод?
ты
you (singular)
купить
to buy (perfective)
из
out of
что-нибудь
anything / something (unspecified)
Questions & Answers about Ты купил что-нибудь из ягод?
Why is the word for berries ягод here instead of ягоды?
The word ягод is the genitive plural form of ягода (berry). In the genitive plural, feminine nouns that end in -а get a zero ending, meaning you simply drop the -а. We need the genitive case here because the noun follows the preposition из.
Why does the sentence use что-нибудь из ягод (anything out of berries) instead of translating 'any berries' directly?
Using что-нибудь из plus the genitive plural is a very natural Russian way to ask about a general category of things. You will hear this pattern a lot with food and shopping, such as asking for что-нибудь из мяса (any meat) or что-нибудь из напитков (any drinks).
Could I use что-то instead of что-нибудь?
It is much better to use что-нибудь in this question. The word что-то usually refers to a specific 'something' that actually exists, even if you do not know exactly what it is. Что-нибудь means 'anything at all' and is the natural choice for questions, requests, or hypothetical situations.
Does the preposition из always force the noun into the genitive case?
Yes! The preposition из always takes the genitive case. While you might know it best as meaning 'from' a city or country, here it acts to mean 'out of' or 'from among' a broader group of items.