imouto ha maiasa banana to yooguruto dake tabete, isoide gakkou he dekakemasu.

は marks 妹 as the topic of the sentence: As for my younger sister...

That means the sentence is presenting information about her:

• 妹は ... 食べて、出かけます
• As for my younger sister, she eats ... and leaves ...

If you used が instead, it would sound more like you are identifying her specifically as the one who does the action, often with a stronger focus or contrast:

• 妹が ... = It is my younger sister who ...

In a plain descriptive sentence like this, は is very natural.

毎朝 means every morning. It tells you when the actions happen.

Japanese time expressions are often placed near the beginning of the sentence, before the main action:

• 妹は 毎朝 ... 食べて、... 出かけます。

That placement is very natural, but Japanese word order is more flexible than English. As long as the particles make the relationships clear, the time phrase can move around somewhat.

Here, と is the particle used to connect nouns in the sense of and.

So:

• バナナとヨーグルト = bananas and yogurt

This と is used when listing items as a complete pair/list.

Compare:

• バナナとヨーグルト = bananas and yogurt
• バナナやヨーグルト = things like bananas and yogurt / bananas, yogurt, etc.

So と is the right choice here because the sentence is naming exactly what she eats.

だけ means only.

In this sentence:

• バナナとヨーグルトだけ食べて means
• eats only bananas and yogurt, and then...

Because だけ comes after the whole noun phrase バナナとヨーグルト, it applies to the whole combination, not just ヨーグルト by itself.

So the idea is:

• She eats nothing but bananas and yogurt.

It applies to both together.

The structure is:

• [バナナとヨーグルト] だけ

So the entire phrase bananas and yogurt is what is limited by only.

If the sentence were trying to say only yogurt, it would look more like:

• バナナとヨーグルトの中でヨーグルトだけ... or something similarly more specific.

As written, the natural reading is:

• only bananas and yogurt

食べて is the て-form of 食べる. Here it connects one action to the next.

So:

• 食べて、出かけます means
• eat(s), and then leave(s)

Japanese often uses the て-form to link actions in sequence:

• 起きて、顔を洗って、朝ご飯を食べます。
• wake up, wash one’s face, and eat breakfast

Only the final verb needs to show the sentence’s politeness level:

• 食べて、出かけます not
• 食べます、出かけます in this kind of connected structure

Yes, normally it suggests a natural sequence:

1. she eats only bananas and yogurt
2. then she leaves for school

The て-form can connect actions in several ways, but in a sentence like this, the most natural interpretation is and then.

So the sentence feels like a morning routine:

• she eats a simple breakfast,
• then hurriedly leaves for school.

Yes. 急いで is the て-form of 急ぐ.

But here it is not simply linking two completely separate actions the way 食べて does. It works more like an adverbial expression:

• 急いで出かけます = leave in a hurry = hurry off

So you can think of it as describing how she leaves.

A useful comparison:

• 食べて、出かけます = eats, and then leaves
• 急いで出かけます = leaves hurriedly / hurries off

The comma helps separate the first action from the second part of the sentence:

• バナナとヨーグルトだけ食べて、急いで学校へ出かけます。

It makes the sentence easier to read.

Japanese commas are often more flexible than English commas. Some writers might include one here, and some might leave it out. The meaning does not change much.

へ marks the direction or destination of movement.

So:

• 学校へ出かけます means
• leave/go out for school or more literally
• head toward school

With movement verbs, へ and に can often both be used:

• 学校へ行きます
• 学校に行きます

The difference is small:

• へ emphasizes direction
• に emphasizes destination

Here, へ sounds perfectly natural.

出かけます means go out, head out, or leave the house. It focuses on the act of going out from where you are.

行きます just means go.

So:

• 学校へ行きます = goes to school
• 学校へ出かけます = heads out for school / leaves for school

In this sentence, 出かけます gives a nice sense of a morning departure from home.

In Japanese, when verbs are connected in a sentence, the politeness is usually shown on the final verb.

So:

• 食べて、出かけます is normal polite Japanese.

The first verb appears in て-form, which does not itself show plain vs. polite in the same way a final verb does. The sentence’s overall politeness is carried by the ending 出かけます.

This is completely standard.

Yes. After 妹は, Japanese does not keep repeating the subject.

So the sentence is understood as:

• As for my younger sister, she eats only bananas and yogurt every morning and hurriedly leaves for school.

Japanese often leaves out subjects and objects when they are already clear from context. Since 妹は sets the topic at the beginning, everything after that is understood to be about her unless something changes.

By itself, 妹 means younger sister.

In an isolated sentence like this, English often translates it as my younger sister because that is the most natural assumption. Japanese often leaves possession unstated when it is obvious from context.

So 妹は usually means:

• my younger sister as the topic

If the speaker meant someone else’s younger sister, the sentence would often make that clearer from context or wording.

Yes. Normal Japanese writing would usually be:

妹は毎朝バナナとヨーグルトだけ食べて、急いで学校へ出かけます。

The spaces in your version are there to help learners see the parts more easily. Japanese normally does not use spaces between words like English does.