hiruyasumi ni konbini de onigiri to sarada wo katte, kouen de tabeta.

に marks the time when something happens. So 昼休みに means at / during lunch break.

A useful note: not every time word needs に, but many specific time expressions do. In this sentence, 昼休みに sounds very natural.

Here, で marks the place where an action happens.

So:

• コンビニで買って = bought at the convenience store

Japanese often uses:

• で for the place where you do something
• に for a destination or a point in time

That is why コンビニに買って would be wrong here.

For the same reason: 公園で marks the place where the action 食べた happened.

So the sentence has two action locations:

• コンビニで → where the buying happened
• 公園で → where the eating happened

Here, と means and between nouns.

So:

• おにぎりとサラダ = rice balls and salad

This is a straightforward, complete listing of the items.

Because おにぎりとサラダ is one combined noun phrase, and the whole phrase is the object of 買って.

So:

• おにぎりとサラダを買って = bought rice balls and salad

You do not need to say おにぎりをサラダを.

In this sentence, おにぎりとサラダ is the object of 買う: those are the things that were bought.

Then the sentence continues with 食べた. Japanese often links actions this way without repeating everything.

So the idea is:

• bought rice balls and salad,
• then ate them in the park

The object is understood with the second verb even though it is not repeated.

The て-form is used to connect verbs. Here it links two actions in sequence:

• 買って、食べた = bought, and ate

It often implies that the first action happened before the second one.

So this sentence describes a natural sequence:

1. bought the food at the convenience store
2. ate it in the park

When verbs are linked with the て-form, the final verb usually carries the tense for the whole sequence.

So:

• 買って、食べた means bought and ate
• you do not need 買った、食べた here

The first verb stays in て-form, and the last verb shows that the sequence is in the past.

Japanese very often omits the subject when it is clear from context.

So this sentence could mean:

• I bought ... and ate ...
• we bought ... and ate ...
• he/she bought ... and ate ...

The exact subject depends on the surrounding context. In English, you usually need to say it; in Japanese, you often do not.

Because Japanese does not need a topic marker in every sentence. If the topic is already understood, it is often omitted.

For example, if you wanted to make the subject/topic explicit, you could say:

• 私は昼休みにコンビニでおにぎりとサラダを買って、公園で食べた。

But if everyone already knows who is being talked about, leaving out 私は sounds natural.

To some extent, yes. Japanese word order is more flexible than English because the particles show each word’s role.

For example, these parts can sometimes move around:

• 昼休みに
• コンビニで
• 公園で

However, the verb usually comes at the end of its clause, and the original order sounds very natural and easy to follow.

The comma helps show a pause and makes the sentence easier to read:

• 買って、公園で食べた。

It is not a separate grammatical particle. It just marks a break between the two linked actions. In many cases, the sentence would still be understandable without it, especially in casual writing.

They are:

• 買って → dictionary form 買う (to buy)
• 食べた → dictionary form 食べる (to eat)

Their forms here are:

• 買って = て-form of 買う
• 食べた = past plain form of 食べる

So the sentence uses one linked verb and one final past-tense verb.