Learn Hardcore Czech: Můj bratr dnes jenom spí doma. - Today my brother is just sleeping at home.

můj bratr = nominative (who is doing the action? my brother)
mého bratra = genitive/accusative (used for objects, after some prepositions, etc.)

Examples:

Můj bratr dnes jenom spí doma.
→ My brother is the one doing the sleeping → nominative.

Compare:

Vidím svého bratra. – I see my brother.
Here, svého bratra is the object of vidím, so it’s in accusative, not nominative.

What is the difference between jenom and jen? Are both correct?

Yes, both jenom and jen are correct and very common. They both mean “only/just”.

jen is a bit shorter and slightly more colloquial.
jenom can feel a bit more neutral or slightly emphasized in some contexts, but in everyday speech they often sound interchangeable.

In your sentence, you could say:

Můj bratr dnes jenom spí doma.
Můj bratr dnes jen spí doma.

Both are fine and mean the same thing in normal conversation.

Does the position of jenom change the meaning? For example, jenom spí doma vs spí jenom doma?

Yes, the position of jenom is important and can change what is being limited:

Můj bratr dnes jenom spí doma.
→ The activity is limited: today he is only sleeping (and not doing anything else).
English idea: Today my brother is just sleeping at home.
Můj bratr dnes spí jenom doma.
→ The place is limited: today he sleeps only at home (and not anywhere else).
English idea: Today my brother sleeps only at home (not at work, not elsewhere).

Czech often uses word order to show what “only” belongs to. Place jen/jenom right before the word or phrase you want to limit.

Can the word order change? For example, can I say Dnes můj bratr jenom spí doma?

Yes, Czech word order is more flexible than English. You can move words to change emphasis:

Můj bratr dnes jenom spí doma.
Neutral, light emphasis on my brother as the topic: what is my brother doing today?
Dnes můj bratr jenom spí doma.
Puts more focus on dnes (today). Often used when contrasting with other days:
Today, my brother is just sleeping at home (unlike usual).
Doma dnes můj bratr jenom spí.
Emphasis on doma (at home) – maybe you just mentioned other places.

The basic meaning stays the same, but the focus and what sounds “new” in the sentence changes with word order.

Why is the verb spí and not spát?

spát is the infinitive form (to sleep).
In the sentence, you need a conjugated present tense form for he sleeps / he is sleeping:

Verb spát (to sleep) in present tense:

já spím – I sleep
ty spíš – you sleep (sg., informal)
on/ona/ono spí – he/she/it sleeps
my spíme – we sleep
vy spíte – you sleep (pl. or formal)
oni spí – they sleep

Since můj bratr = he, you use spí (3rd person singular).

Why is there no word for “is” like in English “is sleeping”?

Czech does not have a separate present continuous tense like English (is sleeping, is working). It usually uses only the simple present form:

spí = sleeps or is sleeping
pracuje = works or is working

So:

Můj bratr dnes jenom spí doma.
can mean both:
- My brother sleeps at home today.
- My brother is just sleeping at home today.

The context (especially the word dnes) suggests a “right-now / today” meaning, similar to the English continuous.

What exactly does doma mean? How is it different from v domě or dům?

These are related but different:

doma = at home (location, adverb)
→ Můj bratr je dnes doma. – My brother is at home today.
v domě = in the house (literally inside a house, more physical/neutral)
→ Spí v domě na konci ulice. – He sleeps in the house at the end of the street.
dům = a house (the building itself, noun)
→ To je velký dům. – That is a big house.

In everyday speech, doma is what you normally use for “at home”, including your sentence:
Můj bratr dnes jenom spí doma.

Can we omit můj or dnes in this sentence?

Yes, you can omit some words if the meaning is clear from context:

Omitting můj:
- Bratr dnes jenom spí doma.
  If it’s obvious we’re talking about my brother (for example, in a conversation about your family), můj is not necessary.
  With můj, you explicitly say my brother; without it, it’s more neutral and could mean “the brother (mine/ours/his…)” depending on context.
Omitting dnes:
- Můj bratr jenom spí doma.
  Now it means My brother only sleeps at home (in general), not specifically today.
  dnes limits the action to today.

Why don’t we say On můj bratr dnes jenom spí doma with on (he)?

In Czech, subject pronouns (like I, you, he, she) are usually dropped, because the verb ending and the noun phrase already show who is doing the action.

Můj bratr dnes jenom spí doma. – completely natural.
On dnes jenom spí doma. – also possible; here on replaces můj bratr.
On, můj bratr, dnes jenom spí doma. – possible but sounds more like emphasis/explanation:
He, my brother, is just sleeping at home today.

Using both on and můj bratr together in a straightforward sentence is normally unnecessary and can sound heavy or overly emphatic.

Is můj bratr neutral, formal, or informal? Could I say můj brácha instead?

můj bratr is neutral/standard, suitable in both spoken and written Czech, and in formal or neutral contexts.
můj brácha is more colloquial/informal, like my bro / my brother in casual speech.

Examples:

Talking to a friend:
Můj brácha dnes jenom spí doma. – very natural in casual conversation.
Writing something more formal (e.g. an essay):
Můj bratr dnes jenom spí doma. – better choice here.

What is the difference between dnes and dneska?

Both dnes and dneska mean “today”.

dnes – a bit more neutral, common in both writing and speech.
dneska – slightly more colloquial, very common in spoken Czech.

You can say:

Můj bratr dnes jenom spí doma.
Můj bratr dneska jenom spí doma.

In everyday conversation, you will hear dneska a lot, but dnes never sounds wrong.