Относительное местоимение «который» соединяет части предложения.

It means relative pronoun.

In Russian grammar, a relative pronoun is a word like который that refers back to a noun and introduces a subordinate clause, similar to English who, which, or sometimes that.

Example:

• Это книга, которую я купил.
• This is the book that I bought.

Here которую refers back to книга and links the two parts of the sentence.

Because the sentence is talking about the word который itself, not using it normally inside the sentence.

Russian often puts cited words or terms in « ». In English, we might use quotation marks or italics for the same purpose.

So here:

• «который» = the word который
• not an actual relative clause inside this sentence

Because it agrees with местоимение.

Russian adjectives must agree with the noun they describe in:

• gender
• number
• case

Here:

• местоимение is neuter
• singular
• nominative

So the adjective must also be:

• относительное

Compare:

• относительный вопрос — masculine
• относительная форма — feminine
• относительное местоимение — neuter

Here который is just being mentioned as a dictionary form, so it appears in its basic form:

• nominative singular masculine

This is the form you usually see in vocabulary lists.

But in real sentences, который changes form depending on:

1. the noun it refers to
2. its grammatical role in the subordinate clause

For example:

• дом, который стоит на холме — nominative
• дом, который я вижу — accusative
• дом, в котором я живу — prepositional

So который is a highly inflected word.

Соединяет means connects or joins.

It is the:

• 3rd person singular
• present tense
• of the verb соединять — to connect

Why singular? Because the subject is singular:

• Относительное местоимение ... соединяет ...
• The relative pronoun ... connects ...

Russian present-tense verbs change depending on the subject:

• я соединяю
• ты соединяешь
• он/она/оно соединяет
• они соединяют

Also, the present tense here expresses a general fact, like in English:

• Water boils at 100°C.
• A relative pronoun connects parts of a sentence.

This phrase breaks down like this:

• части = parts
• предложения = of the sentence

So части предложения means parts of the sentence.

Grammatically:

• части is the direct object of соединяет
• предложения is in the genitive singular, because Russian commonly uses the genitive after a noun like part

A similar pattern in English is:

• the door of the house
• the pages of the book
• the parts of the sentence

So предложения here does not mean plural sentences. It is singular genitive: of the sentence.

That is a very good question.

In practical grammar, который connects one clause to another clause inside a larger sentence. So from an English-speaking learner’s perspective, it is often clearer to think:

• который links clauses
• or который introduces a relative clause

Russian grammar books, especially school-style explanations, may say соединяет части предложения, which literally means connects parts of a sentence. In this context, those parts are basically the main clause and the subordinate clause.

So the sentence is not wrong; it is just using traditional grammar wording.

Russian который can often correspond to English:

• who
• which
• that

But Russian uses it more explicitly than English does.

For example:

• The man who lives there

  • человек, который там живёт

• The book that I bought

  • книга, которую я купил

A major difference is that Russian который changes form:

• gender: который / которая / которое / которые
• case: которого / которому / которым, etc.

English relative pronouns change much less.

Another important point:

• In Russian, the gender and number of который depend on the noun it refers to.
• The case of который depends on its role inside the relative clause.

It is pronounced roughly like:

• KO-ta-ryi

The stress is on the first syllable:

• кОторый

A rough English approximation is not perfect, but something like:

• KOH-tuh-rih-y

The final -ый does not sound like English ee. It has the Russian vowel ы, which is a sound English does not really have.

Because Russian has no articles.

English says:

• the relative pronoun
• a relative pronoun

Russian simply says:

• относительное местоимение

Whether it means a, the, or something more general depends on context. Here it is a general grammatical statement, so in English the relative pronoun sounds natural because a specific pronoun, который, is being discussed.

Yes. Russian word order is more flexible than English word order.

The neutral order here is:

• Относительное местоимение «который» соединяет части предложения.

This is the most straightforward order for a definition or explanation:

1. subject
2. verb
3. object

You could change the order for emphasis, but in a grammar explanation this standard order is the most natural and clear.