Этот символ означает дверь.

Because символ is a masculine singular noun, and the demonstrative this has to agree with it.

• этот = this (masculine singular)
• эта = this (feminine singular)
• это = this (neuter singular)
• эти = these (plural)

Since символ is masculine, you say этот символ = this symbol.

A very common clue in Russian is the noun ending in the dictionary form:

• nouns ending in a consonant are often masculine
• nouns ending in -а / -я are often feminine
• nouns ending in -о / -е are often neuter

символ ends in a consonant, so it is masculine.

Yes, дверь is the direct object, so it is in the accusative case. But for this noun, the accusative looks the same as the nominative.

Here is why:

• дверь is a feminine inanimate noun
• for many feminine nouns of this type, nominative and accusative singular are identical

So:

• nominative: дверь
• accusative: дверь

That is why the sentence uses дверь with no visible change.

• Этот — nominative masculine singular
• символ — nominative singular
• означает — verb
• дверь — accusative singular

So the structure is basically:

This symbol + means + door

означает is the 3rd person singular present tense form of означать.

So:

• я означаю = I mean / signify
• ты означаешь = you mean / signify
• он / она / оно означает = he / she / it means / signifies
• они означают = they mean / signify

Since the subject is этот символ (this symbol), Russian uses означает.

Usually yes in this kind of sentence, but it can also be understood as:

• means
• signifies
• indicates

So Этот символ означает дверь can mean something like:

• This symbol means door
• This symbol signifies a door
• This symbol indicates a door

The exact English wording depends on context.

Russian does not have articles like English a/an/the.

So символ could mean:

• a symbol
• the symbol

and дверь could mean:

• a door
• the door
• door in a general label-like sense

Context tells you which English article makes the most sense.

Yes. Russian word order is more flexible than English because case endings show the grammatical roles.

The most neutral order here is:

Этот символ означает дверь.

But other orders are possible for emphasis, for example:

• Дверь означает этот символ. — grammatically possible, but now it sounds like door is the subject, so the meaning changes
• Этот символ дверь означает. — possible, but marked/emphatic

For a learner, the safest choice is the original neutral order: Этот символ означает дверь.

The stress is:

• Э́тот
• си́мвол
• означа́ет
• дверь (monosyllabic, so the stress is on that only syllable)

A rough pronunciation guide:

EH-tuht SEEM-vuhl uz-nuh-CHA-yet dverʹ

A few notes:

• этот: the first э is stressed
• означает: stress is on -ча-
• дверь ends in a soft consonant because of ь

The soft sign ь does not have its own sound. Its job is to make the preceding consonant soft (palatalized).

So in дверь, the final р is soft.

It also often helps show the noun type. Many feminine nouns end in -ь, for example:

• дверь = door
• ночь = night
• тетрадь = notebook

They are related, but not always identical.

• символ = symbol
• знак = sign, mark, symbol

In many contexts either could work, but the nuance can differ:

• символ often feels more like symbol
• знак often feels more like sign

So if you are literally talking about an icon or pictogram, both may appear depending on context, but символ is perfectly natural here.

Not in this sentence.

Because символ is masculine, the correct demonstrative is:

• этот символ

Not:

• эта символ ❌
• это символ ❌

However, Это символ can be correct in a different structure, where это means this is or it is:

• Это символ. = This is a symbol.

So:

• Этот символ = this symbol
• Это символ = this is a symbol

That difference is very important.

It is grammatically correct and natural. It sounds especially normal in contexts like:

• a museum label
• a language or symbol explanation
• a sign system
• a guidebook
• software or interface instructions

For example, if someone is explaining icons on a map, Этот символ означает дверь sounds completely reasonable.