Лучше хранить документы в папке.

Yes. Лучше means better, but in sentences like this it often has the sense of it is better to... or it's best to....

So:

• Лучше хранить документы в папке.
• literally: Better to store documents in a folder.
• natural English: It’s better to keep the documents in a folder.

Russian often leaves out it is in this kind of sentence.

Because after лучше Russian often uses the infinitive to express a general recommendation or advice.

So:

• Лучше хранить... = It’s better to store/keep...
• Лучше сделать... = It’s better to do...
• Лучше подождать... = It’s better to wait...

This structure is very common in Russian when talking about what is advisable in general.

Хранить means to store, to keep, or to keep محفوظ / in safekeeping depending on context.

In this sentence, хранить документы means something like:

• to keep documents
• to store documents
• to keep documents safely/organized

It is about where the documents are kept over time, not just putting them somewhere once.

Документы is the plural form of документ (document).

Here it is the direct object of хранить, so it should be in the accusative plural. For inanimate masculine nouns like документ, the accusative plural is the same as the nominative plural:

• nominative plural: документы
• accusative plural: документы

So:

• хранить что? → документы

That is why the form stays документы.

Because в папке uses the prepositional case and means in the folder as a location.

Compare:

• в папке = in the folder → location
• в папку = into the folder → direction/result of movement

Here the idea is where the documents are kept, not where they are being moved:

• хранить документы в папке = to keep documents in a folder

If you said:

• положить документы в папку

that would mean to put the documents into the folder.

Папке is the prepositional singular form of папка.

The dictionary form is:

• папка = folder

After в when it means location, Russian normally uses the prepositional case:

• в папке = in the folder

This is why папка changes to папке.

It can mean either one, depending on context.

Папка can be:

• a physical folder for papers
• a file folder on a computer

In Лучше хранить документы в папке, many learners will first imagine a physical folder, but the sentence could also work in a digital context if the surrounding situation makes that clear.

Because this is an impersonal, general statement. Russian often omits a subject when the meaning is something like:

• it is better to...
• one should...
• it’s advisable to...

So instead of saying something equivalent to You should keep the documents in a folder, Russian can simply say:

• Лучше хранить документы в папке.

It sounds general and natural.

Yes. Russian word order is flexible, though the original version is very natural.

Original:

• Лучше хранить документы в папке.

Other possible orders:

• Документы лучше хранить в папке.
• В папке лучше хранить документы.

These versions all mean roughly the same thing, but the emphasis changes a little:

• Документы лучше хранить в папке puts more focus on documents
• В папке лучше хранить документы puts more focus on in a folder

The original is a neutral, standard way to say it.

Both can sometimes translate as keep, but they are not always the same.

• хранить = to store, keep, preserve, keep safely
• держать = to hold, keep, have something somewhere

In this sentence, хранить sounds more appropriate because documents are usually stored or kept safely/organized.

• хранить документы в папке = a very natural collocation

Держать документы в папке is possible in some contexts, but it can sound a bit less formal or less specifically about storage.

Хранить is imperfective, and that fits because the sentence talks about a general habit or ongoing state: how documents should be kept.

Imperfective is used for:

• general actions
• repeated actions
• ongoing processes
• habits

This sentence is general advice, so imperfective is exactly what you want.

A perfective verb would not sound natural here in the same way, because perfective usually focuses on a completed action. For example, if you wanted to say put the documents into a folder, you would use a different verb such as:

• Лучше положить документы в папку.

That means It’s better to put the documents into a folder, focusing on the action of placing them there, not the continuing state of keeping them there.

Sometimes yes, in natural English translation.

Russian лучше + infinitive often expresses advice, so depending on context:

• Лучше хранить документы в папке. could be translated as
• It’s better to keep documents in a folder.
• You should keep documents in a folder.
• It’s best to keep documents in a folder.

But grammatically, лучше still literally means better, not should. The should meaning comes from the whole expression.

Most naturally, it sounds like documents in general.

That is because there is no word like эти (these) or мои (my), and the sentence has a general advisory tone:

• Лучше хранить документы в папке. = It’s better to keep documents in a folder.

However, in the right context it could also refer to a specific set of documents if everyone already knows which documents are being discussed. Russian often leaves that to context.