У грудні я вдома.

In December I am at home.

Breakdown of У грудні я вдома.

• я: I
• у: in
• вдома: at home
• грудень: December

Questions & Answers about У грудні я вдома.

Why does грудень become грудні here?

Because after у / в meaning in with a month name, Ukrainian normally uses the locative case.

So:

• dictionary form: грудень = December
• after у / в: у грудні = in December

This is the regular pattern for months:

• у січні = in January
• у лютому = in February
• у березні = in March
• у грудні = in December

So грудні is not a different word; it is the locative form of грудень.

What does у mean here, and why is it у instead of в?

Here у means in.

Both у and в can mean in in Ukrainian. Very often the choice depends on sound and ease of pronunciation, not meaning. Ukrainian likes to avoid awkward sound combinations.

So:

• У грудні я вдома.
• В грудні я вдома.

Both can be understood, but у грудні sounds smoother and more natural to many speakers here.

A useful rule: Ukrainian often switches between у and в for euphony, while the meaning stays the same.

Why is there no word for in the sentence?