Learn Hardcore Russian: Вечером я останусь дома.

вечером means in the evening. It’s the instrumental-case form of вечер used adverbially to indicate time without a preposition. Russian often uses this pattern for parts of the day: утром (“in the morning”), днём (“in the afternoon”), вечером (“in the evening”).

Why is the pronoun я included? Can I drop it?

Russian is pro-drop, so you can omit я because останусь already marks first-person singular. Saying Вечером останусь дома is perfectly natural. Including я adds clarity or emphasis.

What is the verb останусь, and what aspect and tense is it?

Останусь is the first-person singular future tense of the perfective verb остаться (“to stay, remain”). Being perfective, it denotes a single complete action in the future: “I will stay at home.” The imperfective counterpart is оставаться, which forms the future as я буду оставаться (“I will be staying”).

How does останусь дома differ from я буду дома?

Останусь дома emphasizes the decision or action of staying put at home. Я буду дома simply states a future location (“I will be at home”) without the nuance of choosing not to go out.

Why is дома used without a preposition? What case is it?

Дома is an adverb meaning at home, derived from the old locative of дом. Modern Russian treats it as an indeclinable adverb, so no preposition or case marking is needed.

Can I say в доме instead of дома?

Not for “at home.” В доме (prepositional case) means inside the house (physically in the building). Дома means being at home in the sense of one’s own residence.

Where does the stress fall in останусь?

The stress is on the second syllable: оста́нусь (os-TA-nusʹ). In the infinitive остаться, the stress remains: оста́ться.

Is the word order flexible? Could I place вечером elsewhere?

Word order is fairly flexible. The neutral sequence is Time – Subject – Verb – Place: Вечером я останусь дома. You can also say Я останусь дома вечером for emphasis or contrast, but вечером at the beginning is most common to set the time context.