У цій папці лежать важливі документи та копії квитків.

It is the locative case, because the sentence is talking about something being in a place: in this folder.

• у / в = in
• ця = this (feminine singular, dictionary form)
• цій = locative feminine singular of ця
• папка = folder
• папці = locative singular of папка

So:

• ця папка = this folder
• у цій папці = in this folder

Also, у and в are just two forms of the same preposition. Ukrainian often chooses one or the other for smoother pronunciation.

Because nouns often change their ending in the locative case.

Here:

• папка → папці

This is a normal pattern for many feminine nouns ending in -ка. The к changes to ц before the ending:

• книга → у книзі
• рука → у руці
• папка → у папці

So this is not random; it is part of a common stem change in Ukrainian declension.

Лежати literally means to lie or to be lying, but in Ukrainian it is often used naturally for objects that are physically located somewhere, especially things like papers, books, clothes, and other items.

So лежать here suggests that the documents and copies are lying/kept in the folder.

Why not є?

• In the present tense, Ukrainian often omits є altogether.
• A sentence like У цій папці важливі документи... can work, but лежать sounds more concrete and natural because the items are physically there in the folder.

So лежать is not just exist; it gives a more physical sense of where the objects are.

Because the subject is plural.

The things lying in the folder are:

• важливі документи
• копії квитків

Together, that is a plural subject, so the verb must also be plural:

• лежить = lies / is lying for singular
• лежать = lie / are lying for plural

For example:

• У папці лежить документ. = A document is in the folder.
• У папці лежать документи. = Documents are in the folder.

Документи is nominative plural.

It is the subject of the sentence — the things that are doing the action of лежать.

Forms:

• документ = singular
• документи = plural

So in this sentence, документи means documents and functions as part of the plural subject.

Because adjectives must agree with the nouns they describe.

Here, документи is:

• plural
• nominative
• inanimate masculine noun in plural

So the adjective also takes the nominative plural form:

• важливий документ = an important document
• важливі документи = important documents

The adjective важливі is the plural form used to match plural nouns.

This is a very common Ukrainian noun structure:

• копії = copies
• квитків = of tickets

So literally it is copies of tickets.

Why is квитків in the genitive?

Because after a noun like копія / копії, Ukrainian often uses another noun in the genitive to show what the copies are copies of.

Forms:

• копія = copy
• копії = copies
• квиток = ticket
• квитків = of tickets / tickets (genitive plural)

So:

• копія квитка = a copy of a ticket
• копії квитків = copies of tickets

Because квитків is the genitive plural form of квиток.

Compare:

• квиток = ticket
• квитка = of a ticket (genitive singular)
• квитків = of tickets (genitive plural)

So:

• копія квитка = copy of a ticket
• копії квитків = copies of tickets

Both nouns are plural in the sentence:

• копії = copies
• квитків = of tickets

Both та and і can mean and.

In this sentence, та simply joins two noun phrases:

• важливі документи
• копії квитків

So:

• документи та копії = documents and copies

Why choose та?

Usually for style or sound. Ukrainian often alternates between і, й, and та to make the sentence flow better and avoid awkward sound combinations.

In this sentence, та does not change the meaning in any important way.

Yes, you could say it differently.

For example:

• У цій папці лежать важливі документи та копії квитків.
• Важливі документи та копії квитків лежать у цій папці.

Both are grammatical.

The difference is mainly focus:

• У цій папці... puts the location first, as the topic.
• Важливі документи... puts the items themselves first.

Ukrainian word order is more flexible than English word order, but the different orders can sound more or less natural depending on what you want to emphasize.

Not necessarily. In Ukrainian, лежати is often used quite naturally for objects that are placed somewhere, especially papers and similar items.

So here it does not sound oddly literal. It simply suggests that the documents and ticket copies are there in the folder.

English usually prefers something like:

• There are important documents and copies of tickets in this folder
• This folder contains important documents and copies of tickets

But Ukrainian can very naturally use лежать in this kind of sentence.

Because Ukrainian does not have articles like a and the.

English says:

• the folder
• the documents

Ukrainian does not use separate article words for that. Instead, definiteness is usually understood from:

• context
• word order
• demonstratives like цей / ця / це / ці = this

So цій already gives the idea of this folder, but there is no separate word corresponding to the.