Она продала старый телефон.

• Она = she
• продала = sold
• старый = old
• телефон = phone

So the sentence is She sold the old phone.

Because this is the past tense and the subject is feminine singular.

In Russian past tense, verbs agree with gender and number:

• продал = he sold
• продала = she sold
• продало = it sold
• продали = they sold

Since она means she, the verb must be продала.

The dictionary form is продать.

That is the infinitive, meaning to sell.

So:

• продать = to sell
• продала = she sold

This is an aspect question.

Russian has two aspects:

• perfective: focuses on a completed action
• imperfective: focuses on process, repetition, or background action

Here:

• продать → perfective
• продавать → imperfective

So:

• Она продала старый телефон = She sold the old phone / She has sold the old phone
  The sale is presented as completed.

Compare:

• Она продавала старый телефон = She was selling the old phone / She used to sell old phones / She was trying to sell the old phone, depending on context.

Because старый describes телефон, and both words must match in gender, number, and case.

Here телефон is:

• masculine
• singular
• inanimate

It is the direct object of the verb продала, so it is in the accusative case.

For masculine inanimate nouns, the accusative looks the same as the nominative:

• старый телефон = nominative
• старый телефон = accusative

So the form does not change here.

Because телефон is a masculine inanimate noun, and in Russian the accusative singular of masculine inanimate nouns is the same as the nominative singular.

So:

• nominative: телефон
• accusative: телефон

That is why you see:

• Она продала телефон

But with an animate masculine noun, the accusative would look different:

• Я вижу брата = I see (my) brother

For the same reason: старый agrees with телефон, and телефон is masculine singular inanimate accusative, which has the same form as nominative.

Compare:

• Я вижу старый телефон = I see an old phone
• Я вижу старого друга = I see an old friend

Why the difference?

• телефон is inanimate → accusative = nominative
• друг is animate → accusative = genitive-like form

So:

• старый телефон
• старого друга

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

The neutral order here is:

• Она продала старый телефон.

But you could also hear:

• Старый телефон она продала.
• Продала она старый телефон.

These usually change the emphasis, not the basic meaning.

For example:

• Старый телефон она продала puts emphasis on the old phone
• Она продала старый телефон is the most straightforward, neutral version

Yes, often you can.

Russian often omits subject pronouns when the meaning is clear from the verb form or from context.

So:

• Продала старый телефон.

can still mean:

• She sold the old phone

Because продала already shows:

• past tense
• feminine singular

Still, speakers may include она for clarity, contrast, or emphasis.

Usually the most natural basic translation is:

• She sold the old phone

But because the verb is perfective, it can sometimes also be understood as:

• She has sold the old phone

Russian does not have a separate form exactly like the English present perfect. Context determines which English translation sounds best.

Because Russian has no articles like a/an or the.

So старый телефон can mean:

• an old phone
• the old phone

Context tells you which one is meant.

In this sentence, English will often use the old phone if the phone is already known in context.

Adjectives in Russian agree with the nouns they describe.

Here:

• телефон is masculine
• singular
• accusative, but since it is inanimate, it looks like nominative

So the adjective must also be masculine singular in that same pattern:

• старый телефон

If the noun changed, the adjective would change too:

• старая книга = old book
• старое письмо = old letter
• старые телефоны = old phones

The stress is:

• она́
• продала́
• ста́рый
• телефо́н

A simple pronunciation guide:

• она́ ≈ a-NA
• продала́ ≈ pra-da-LA
• ста́рый ≈ STA-riy
• телефо́н ≈ ty-lee-FON

So the whole sentence sounds roughly like:

• a-NA pra-da-LA STA-riy ty-lee-FON

Yes, that is the usual pattern.

Most Russian nouns ending in a hard or soft consonant are masculine:

• телефон
• стол
• магазин

So телефон is masculine, which is why the adjective is старый and not старая or старое.