Скобки помогают добавить одно короткое слово, которое не меняет основной смысл.

Yes. Скобки is the normal Russian word for parentheses / brackets as a pair, so it is commonly used in the plural.

• скобка = one bracket / one parenthesis
• скобки = brackets / parentheses

This is similar to how English often treats parentheses as a plural form.

Because the subject скобки is plural.

• скобки помогают = parentheses help
• singular would be скобка помогает = a bracket helps

So the verb agrees with the subject in number.

After помогать (to help), Russian often uses an infinitive, just like English does.

• помогать + infinitive = to help do something

So:

• Скобки помогают добавить... = Parentheses help add...
• more naturally in English: Parentheses help you add...

This is a very common pattern in Russian.

Because добавить is the second verb in the structure help to add.

There is only one finite verb here: помогают.
The verb добавить stays in the infinitive because it depends on помогают.

Compare:

• Они помогают читать. = They help (someone) read.
• Скобки помогают добавить слово. = Parentheses help add a word.

If you said добавляют, that would make it a separate finite verb: they add, which is not the structure here.

All three words agree with слово.

• слово is neuter singular
• so the numeral/pronoun is одно
• the adjective is короткое

So:

• одно = one for a neuter noun
• короткое = short in neuter singular
• слово = word

This whole phrase means one short word.

It is in the accusative case because it is the direct object of добавить.

However, for inanimate neuter singular nouns, the accusative form is the same as the nominative form. So:

• nominative: одно короткое слово
• accusative: одно короткое слово

That is why it looks unchanged.

Которое refers to слово.

That is why it is:

• neuter → because слово is neuter
• singular → because слово is singular

So:

• слово, которое... = a word that...

This is a relative clause:

• одно короткое слово, которое не меняет основной смысл
• one short word that does not change the main meaning

Both verbs can be related to change, but менять is simpler and very common in everyday Russian.

• менять = to change, alter, switch
• изменять can also mean to change, but it can sound more formal or have other meanings depending on context

Here не меняет основной смысл is the most natural, straightforward way to say does not change the main meaning.

Because this sentence describes a general characteristic, not one specific future result.

• не меняет = does not change
• it describes what this kind of added word is like in general

If you used a perfective verb such as не поменяет or не изменит, it would sound more like a specific completed result in a particular situation.

Here the meaning is more general:

• parentheses help add a short word
• that word does not change the main meaning

So the imperfective is the natural choice.

It is in the accusative case, because it is the direct object of меняет.

• менять что? → основной смысл

But because смысл is an inanimate masculine noun, its accusative singular is the same as its nominative singular:

• nominative: основной смысл
• accusative: основной смысл

So again, the form does not visibly change.

Both are possible, but основной смысл is very natural for main/basic/core meaning.

• основной смысл = the main or essential meaning
• главный смысл = the principal meaning

In this sentence, основной смысл sounds especially natural because it emphasizes that the core meaning stays the same.

No, Russian word order is fairly flexible, but the given order is natural and clear.

• Скобки помогают добавить одно короткое слово, которое не меняет основной смысл.

This order presents the idea smoothly:

1. the subject: скобки
2. what they help do: помогают добавить
3. what gets added: одно короткое слово
4. extra information about that word: которое не меняет основной смысл

You could move words around in Russian, but this version is neutral and easy to understand.

Yes. Russian often leaves out a general you when English would naturally include it.

So:

• Скобки помогают добавить...

can be understood literally as:

• Parentheses help add...

but in more natural English it often becomes:

• Parentheses help you add...

Russian does not need to state you here. It is understood from the context.