Осенью я часто покупаю хурму, а моя подруга — грейпфрут.

Осенью is the instrumental singular of осень (autumn/fall).

Russian often uses the instrumental form of season words as a time expression meaning in ...:

• весной = in spring
• летом = in summer
• осенью = in autumn/fall
• зимой = in winter

So Осенью я часто покупаю хурму means In autumn, I often buy persimmon(s).
You normally do not use в with these common seasonal expressions.

Покупаю is from the imperfective verb покупать. It is used here because the sentence describes a habitual, repeated action: I often buy.

• покупаю = I buy / I am buying
• куплю = I will buy / I’ll buy once

Because часто means often, the imperfective verb is the natural choice.

It is 1st person singular, present tense of покупать.

The ending -ю shows I:

• я покупаю = I buy
• ты покупаешь = you buy
• она покупает = she buys

So even without я, the verb form itself already tells you the subject is I.

Because it is the direct object of the verb покупаю.

The noun хурма is feminine and ends in -а, so in the accusative singular it changes to -у:

• хурма = nominative
• хурму = accusative

This is a very common pattern for feminine nouns:

• книга → книгу
• машина → машину
• подруга → подругу

Because грейпфрут is a masculine inanimate noun, and for masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

So:

• грейпфрут = nominative
• грейпфрут = accusative

Compare:

• Я вижу стол = I see a table
• Я покупаю грейпфрут = I buy grapefruit / a grapefruit

This is why хурму changes, but грейпфрут does not.

In a sentence like this, it often means the fruit as a product in general, not necessarily exactly one piece.

So я часто покупаю хурму can naturally mean something like:

• I often buy persimmons
• I often buy persimmon fruit

The same idea applies to грейпфрут here. Russian often uses singular food nouns in a general sense, where English may prefer a plural or a mass-style translation depending on context.

Here а shows a contrast or comparison: and/as for/whereas.

So the idea is:

• I often buy persimmons, whereas my friend buys grapefruit.

It is not exactly the same as:

• и = simple and
• но = stronger but

In this sentence, а is perfect because the two people are being compared.

They do two different jobs.

1. The comma
There is a comma before а because it joins two clauses:

• Осенью я часто покупаю хурму
• а моя подруга — грейпфрут

2. The dash
The dash shows that the verb покупает is omitted in the second clause because it is understood from the first one.

Full version:

Осенью я часто покупаю хурму, а моя подруга покупает грейпфрут.

Shorter, more natural version:

Осенью я часто покупаю хурму, а моя подруга — грейпфрут.

So the dash marks the missing repeated verb.

Because the possessive pronoun must agree with the noun.

Подруга is a feminine singular noun, so you need:

• моя подруга = my female friend

Compare:

• мой друг = my male friend
• моя подруга = my female friend
• моё окно = my window
• мои друзья = my friends

Usually подруга means female friend.

If someone wants to say girlfriend in the romantic sense, Russian more often uses девушка, depending on context.

So in most neutral learning contexts, моя подруга should be understood as my female friend.

Yes. Russian word order is flexible, and changing it changes the focus or emphasis, not the basic meaning.

This sentence starts with Осенью to set the time frame first:

• Осенью я часто покупаю хурму...

But other orders are also possible, for example:

• Я осенью часто покупаю хурму.
• Я часто покупаю хурму осенью.

The original version sounds natural because it introduces the season first and then contrasts я with моя подруга.

Yes, it could.

Because покупаю already shows I, Russian often drops the subject pronoun:

• Осенью часто покупаю хурму...

However, in this sentence, keeping я is natural because there is a contrast with моя подруга. Using both subjects makes the comparison clearer and more balanced.

Because Russian has no articles.

So nouns like хурму and грейпфрут do not need separate words for a, an, or the. Context tells you whether the meaning is general, indefinite, or definite.

That is why Russian can simply say:

• покупаю хурму
• подруга — грейпфрут

and English has to decide how to translate that naturally from context.