На рынке я купила свежий редис и маленький кочан капусты для салата.

Купила is the past tense feminine singular form of the verb.

• купить = to buy (the infinitive)
• купил = he bought
• купила = she bought

So this sentence tells us the speaker is female.

Also, Russian past tense agrees with gender and number, not person:

• я купил = I bought, said by a man
• я купила = I bought, said by a woman

Russian word order is more flexible than English word order.

Starting with На рынке puts the setting first: At the market...

So the sentence structure feels like:

• At the market, I bought...

This is very natural in Russian. It helps frame the situation before giving the main action.

Рынке is in the prepositional case.

The noun is:

• рынок = market

After на when it means in/on/at a place, Russian usually uses the prepositional case:

• на рынке = at the market

Compare:

• на рынке = at the market, located there
• на рынок = to the market, moving there

Yes, я can often be omitted in Russian if the meaning is clear from context.

However, in the past tense, the verb does not show person clearly the way present tense does. It mainly shows gender and number:

• купила = bought, feminine singular

By adding я, the speaker makes it explicit: I bought.

So:

• Купила свежий редис... can work in context
• Я купила свежий редис... is clearer and more neutral on its own

Because adjectives in Russian must agree with the nouns they describe in:

• gender
• number
• case

Here:

• свежий редис
• маленький кочан

Both редис and кочан are masculine singular nouns.

They are also direct objects, so you might expect accusative. But because they are inanimate masculine singular nouns, the accusative looks the same as the nominative.

So:

• свежий = masculine singular nominative/accusative
• маленький = masculine singular nominative/accusative

Because in Russian, masculine inanimate singular nouns have the same form in the nominative and accusative.

So:

• nominative: редис, кочан
• accusative: редис, кочан

That is why the sentence has:

• купила свежий редис
• купила маленький кочан

If the noun were animate, the form would often be different.

Not necessarily.

Редис can be used as a kind of food/product noun, where the singular refers to the item in a general sense, similar to produce names in English.

So свежий редис can mean:

• fresh radish
• fresh radishes
• fresh radish as a food item

In everyday usage, Russian often does this with foods and produce.

If someone wanted to be more explicitly plural, they might use a different expression depending on context, but свежий редис is natural here.

It literally means a head of cabbage.

• кочан = head, as in a whole compact cabbage
• капуста = cabbage

Russian often uses a structure like this when counting something through a unit or container:

• кочан капусты = a head of cabbage
• compare with things like бутылка воды = a bottle of water

So the sentence is not just saying cabbage in general, but one small head of cabbage.

Because капусты is in the genitive case.

After a noun like кочан, Russian often uses the genitive to show what the head is a head of:

• кочан чего? = a head of what?
• капусты = of cabbage

So:

• кочан капусты = a head of cabbage

This is a very common Russian pattern.

Because the preposition для requires the genitive case.

• салат = salad
• салата = of salad / for salad, after для

So:

• для салата = for salad / for a salad

This is simply the case pattern required by для.

Для салата means for salad or for making a salad in a general, neutral way.

It expresses purpose:

• I bought it for salad

Russian often uses для + genitive to show what something is intended for.

A phrase like на салат can also exist in some contexts, but для салата is the safest and most standard choice here.

The verb купила comes from купить, which is perfective.

Perfective usually presents the action as:

• completed
• whole
• one finished event

So я купила means:

• I bought
• I finished buying

That fits this sentence well, because the speaker is talking about a completed shopping action at the market.

The imperfective покупала would suggest something more like:

• I was buying
• I used to buy
• I bought, with focus on process or repeated action

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

So a noun like рынок, редис, or салат can mean:

• a market / the market
• a radish / the radish / radishes
• a salad / the salad

The exact meaning depends on context.

In this sentence, English would naturally supply articles in translation, but Russian does not need them.

Not in this sentence.

There is an important difference:

• на рынке = at the market → location
• на рынок = to the market → direction or movement

Since the sentence describes where the buying happened, you need на рынке.

If you wanted to say I went to the market, then you would use:

• Я пошла на рынок or Я поехала на рынок