Learn Hardcore Czech: Moje dcera je v knihovně od rána do večera. - My daughter is in the library from morning till evening.

knihovna is the nominative singular form (the basic dictionary form: library).
After the preposition v (meaning in as a location), Czech uses the locative case.

The locative singular of knihovna is knihovně, so:

Moje dcera je v knihovně = My daughter is in the library.

Using v knihovna would be ungrammatical, because knihovna is not in the correct case for that preposition.

What case is used after v here, and does v always take that case?

Here v is followed by knihovně, which is in the locative case.

For modern standard Czech:

v / ve + locative = in, inside, at a place or time
- v knihovně – in the library
- v Praze – in Prague
- v pondělí – on Monday

The preposition v basically always takes the locative case in this spatial / temporal sense. So you can remember:

If you use v to say in/inside/at, the noun goes into locative.

Why is it od rána do večera and not od ráno do večer?

The prepositions od (from, since) and do (to, until) both require the genitive case.

ráno (morning) – nominative → rána – genitive
večer (evening) – nominative → večera – genitive

So:

od rána – from (the) morning
do večera – until (the) evening

Therefore the correct phrase is od rána do večera, not od ráno do večer.

What grammatical case are rána and večera in this phrase?

Both rána and večera are in the genitive singular:

rána – genitive singular of ráno (morning, neuter noun)
večera – genitive singular of večer (evening, masculine noun)

The genitive is required because:

od + genitive
do + genitive

This genitive is very common in time expressions and often has the meaning of from X to Y or until X.

Does od rána do večera mean literally all that time, or more like “all day long”?

od rána do večera can be:

Literal: She really is there from morning until evening.
Idiomatic / approximate: Very often it just means all day long or the whole day, not necessarily to the exact minute.

Context usually tells you whether it’s meant precisely or just as a long time during the day.

What is the difference between moje dcera and má dcera?

Both mean my daughter.

moje dcera – neutral, very common in everyday speech.
má dcera – a short form; sounds a bit more formal, literary, or stylistically elevated.

Examples:

Moje dcera je v knihovně. – perfectly normal, neutral.
Má dcera je v knihovně. – correct, but feels slightly more formal or “styled”.

For everyday spoken Czech, you’re safest using moje dcera.

Can you omit moje and just say Dcera je v knihovně od rána do večera?

You can, but the meaning becomes more context‑dependent.

Moje dcera je v knihovně… – clearly my daughter.
Dcera je v knihovně… – literally “The daughter is in the library…”.

In real conversations, Dcera je v knihovně… might still be understood as my daughter if:

it’s obvious from context that you’re talking about your own daughter, and
she has already been mentioned.

As a learner, if you want to be clear and natural, keep moje:
Moje dcera je v knihovně od rána do večera.

What is the difference between v knihovně and do knihovny?

They express different kinds of meaning:

v knihovně – in the library (location, no movement)
- Moje dcera je v knihovně. – My daughter is in the library.
do knihovny – to the library (movement towards the inside)
- Moje dcera jde do knihovny. – My daughter is going to the library.
- Moje dcera chodí do knihovny. – My daughter goes to the library (regularly).

So use:

v + locative for where someone/something is,
do + genitive for where someone/something is going (into).

Could the word order be V knihovně je moje dcera od rána do večera? Does that change the meaning?

Yes, that word order is correct:

V knihovně je moje dcera od rána do večera.

Czech has fairly flexible word order. The basic meaning stays the same, but the focus changes:

Moje dcera je v knihovně od rána do večera.
- Neutral: you’re mainly talking about your daughter and what she does.
V knihovně je moje dcera od rána do večera.
- Emphasis on the place: It’s in the library that my daughter is from morning till evening (e.g. not somewhere else).

Grammatically both are fine; the difference is mostly in emphasis.

Is the verb je always required in a sentence like this, or can it be dropped?

In standard Czech, in sentences like this, you must use the verb je:

Moje dcera je v knihovně… – correct.
Moje dcera v knihovně… – wrong in normal standard Czech.

Czech does sometimes drop je in:

headlines, slogans, or
very compressed, telegraphic style,

but in normal spoken and written language, especially for learners, always include je in such “X is Y” sentences.

How would the sentence change if I want to say: “My daughters are in the library from morning till evening”?

You need plural forms for daughter and for the verb:

Moje dcery jsou v knihovně od rána do večera.

Breakdown:

moje dcery – my daughters (feminine plural)
jsou – are (3rd person plural of být – to be)
v knihovně – in the library (same form, because it’s still one library in locative)
od rána do večera – from morning till evening (unchanged)

How would I say “My daughter goes to the library from morning till evening”?

If you mean this happens regularly (a habit), you would use a habitual motion verb:

Moje dcera chodí do knihovny od rána do večera.

This suggests that on the days concerned she spends the time from morning till evening at the library (or very often does so).

If you mean right now, today, English “goes” is more like “is (there) from morning till evening” in Czech:

Moje dcera je v knihovně od rána do večera. – She is (spends today) there from morning till evening.

Is there any difference between od rána do večera and od rána až do večera?

Both are correct and very close in meaning:

od rána do večera – from morning till evening
od rána až do večera – from morning right up until evening

Adding až gives a slight feeling of:

emphasizing the endpoint (evening),
sometimes: such a long time, all the way until evening.

But in many contexts, they can be translated the same way and feel almost identical.

How do you pronounce knihovně? The cluster knih- looks difficult.

knihovně is pronounced approximately:

[ˈkɲɪɦɔvɲɛ]

Step by step:

kni- – like knee, but the n is palatal (like Spanish ñ), so something like k-ňi.
-hov- – h is a voiced [ɦ] (a softer, voiced h), then ov like in off but with v at the end.
-ně – again palatal ň
- e, like nye in canyon.

Stress is always on the first syllable in Czech:

KNI-hov-ně (stress on KNI).

Is knihovna only “library”, or can it also mean “bookcase”?

knihovna has two common meanings:

library – an institution / place with books for borrowing or study
- Městská knihovna – city library
bookcase / set of shelves for books – furniture for storing books
- Knihovna je v obýváku. – The bookcase is in the living room.

In your sentence:

Moje dcera je v knihovně od rána do večera.

we naturally interpret knihovna as library, because it makes sense for a person to spend the whole day there.

“In the bookcase” would only be a joke (e.g. a child hiding inside a big cupboard).

What is the gender of dcera and knihovna, and how does that affect the forms in the sentence?

Both dcera (daughter) and knihovna (library) are feminine nouns.

This affects:

The possessive pronoun
- Feminine singular → moje dcera (not můj dcera)
The case endings
- dcera – nominative singular (subject):
  - Moje dcera je… – My daughter is…
- knihovně – locative singular of knihovna:
  - v knihovně – in the library

So the gender determines which forms of moje and which case endings appear in the sentence.