У бібліотеці є п’ятдесят книг.

Because after у / в when you mean a location, Ukrainian uses the locative case.

• бібліотека = library (dictionary form, nominative)
• у бібліотеці = in the library (locative)

So:

• бібліотека → у бібліотеці

This is very common:

• у школі = in the school
• у місті = in the city
• у кімнаті = in the room

If you were talking about motion into the library, you would use a different form, such as в бібліотеку.

Here є means there is / there are.

So the structure is basically:

• У бібліотеці є... = There is/are ... in the library

It shows that something exists or is present in that place.

A very literal breakdown is:

• У бібліотеці = in the library
• є = there is / there are
• п’ятдесят книг = fifty books

It can often be omitted in modern Ukrainian, especially in everyday speech.

So both of these are possible:

• У бібліотеці є п’ятдесят книг.
• У бібліотеці п’ятдесят книг.

The version with є sounds a bit more explicitly existential: it clearly states that the books are present there. The version without є is also natural and common.

This is different from English, where you usually need there is / there are.

Because after numerals 5 and higher, Ukrainian normally uses the genitive plural form of the noun.

So:

• книга = book
• книги = books (nominative plural)
• книг = of books (genitive plural)

After п’ятдесят (fifty), you need книг:

• п’ятдесят книг = fifty books

This is a very important number pattern in Ukrainian:

• 1 → usually nominative singular
• 2, 3, 4 → special plural pattern
• 5+ → genitive plural

Examples:

• одна книга = one book
• дві книги = two books
• п’ять книг = five books

Yes. In this kind of sentence, є can correspond to English is or are.

English changes:

• There is one book
• There are fifty books

But Ukrainian often uses the same form є in existential sentences:

• є одна книга
• є п’ятдесят книг

So you should not expect English-style singular/plural agreement here.

Both у and в can mean in.

Ukrainian often switches between them for euphony—in other words, to make pronunciation smoother.

So both of these can be possible:

• У бібліотеці
• В бібліотеці

Speakers choose the one that sounds better in context. At the beginning of this sentence, У бібліотеці sounds very natural.

This alternation is normal and does not change the meaning.

No. Ukrainian word order is fairly flexible.

У бібліотеці є п’ятдесят книг is a very natural order because it starts with the place and then tells you what exists there.

It is especially common for an existential sentence:

• [place] + є + [thing]

Other word orders are possible, but they change emphasis. For example, moving п’ятдесят книг earlier would sound more marked or contrastive.

So this sentence is not the only possible order, but it is one of the most natural ones.

п’ятдесят is pronounced roughly like pyat-de-SYAT, with the stress on the last syllable: п’ятдеся́т.

The apostrophe in Ukrainian is not like the English apostrophe in don’t or John’s. It shows that the consonant before я, ю, є, ї is not softened and that there is a y-like glide.

So п’я sounds roughly like pya, not like a softened pa.

You will see this in other words too, for example:

• п’ять = five
• ім’я = name
• об’єкт = object

Ukrainian has no articles like a / an / the.

So у бібліотеці can mean:

• in the library
• in a library

Context tells you which one is meant.

This is normal in Ukrainian. The noun itself does not change to show a versus the.

Yes, in practice it can express a very similar idea.

Literally, the sentence is closer to:

• There are fifty books in the library

But in English, that often overlaps with:

• The library has fifty books

Ukrainian frequently uses location or possession structures with є instead of a direct equivalent of English have in some contexts.

So even if the literal structure is different, the real-life meaning can be very close.

A natural negative version is:

• У бібліотеці немає п’ятдесяти книг.

This means:

• There are not fifty books in the library.

Notice two things:

1. є becomes немає
2. The numeral phrase changes form:
   • п’ятдесят книг → п’ятдесяти книг

That happens because немає normally requires the genitive.

So the negative pattern is not just adding a word like English not; it also affects the grammar of what follows.