Learn Hardcore Japanese: ani ha konbini de arubaito wo site imasu. - My older brother works part-time at a convenience store.

兄 literally means “older brother”, but in a neutral statement about your own family, it is understood as “my older brother.”
If you were talking about someone else’s older brother, you’d usually use お兄さん plus their name or title, e.g. 田中さんのお兄さん (Tanaka’s older brother).

So 兄は… is naturally taken as “My older brother…” in English.

What’s the difference between 兄 and お兄さん?

Both are related to “older brother,” but the usage differs:

兄 (あに):
- Used to refer to your own older brother when talking about him to others.
- Feels plain and somewhat formal.
- You don’t normally use 兄 when directly calling him.
お兄さん:
- Polite/neutral; used for someone else’s older brother, or when speaking to an older-brother-type person (e.g., shop clerk, friendly older guy).
- Also used to address your own brother: お兄さん / お兄ちゃん！

In your sentence, 兄はコンビニで… is appropriate because you’re talking about your own brother to someone else.

What does the particle は do after 兄? Why not が?

は marks the topic of the sentence: what you’re talking about.

兄はコンビニでアルバイトをしています。
= As for my older brother, [he] works part-time at a convenience store.

Using が instead would shift the focus to 兄 as the specific subject, often implying contrast or new information:

兄がコンビニでアルバイトをしています。
Could feel like: “It’s my older brother who works at the convenience store (not someone else).”

In everyday explanations about someone, は is the natural choice here.

Why is で used after コンビニ? What’s the difference between コンビニで and コンビニに?

で marks the location where an action takes place.

コンビニでアルバイトをする
= to do part-time work at a convenience store (the workplace).

に usually marks a destination or location of existence:

コンビニに行きます。 = I’m going to the convenience store.
コンビニにいます。 = I’m at the convenience store (existing there).

Because アルバイトをする is an action, we use で: the action happens at the convenience store.

Why do we say アルバイトをする instead of just アルバイトする?

Both forms exist:

アルバイトをする – with を, the more explicit, standard form.
アルバイトする – omits を; common in casual speech.

Some verbs like 勉強する, 運動する often drop を in conversation. With アルバイト, both are acceptable, but using を is slightly more careful/polite and is a good habit for learners.

In the polite progressive form:

アルバイトをしています (textbook/polite, used in your sentence)
アルバイトしています (very natural in speech)

What exactly does しています mean? Is it “is working right now” or “works (habitually)”?

～ている (しています) can express:

An action in progress right now
- 今、兄はコンビニでアルバイトをしています。
  = Right now, my brother is working at the convenience store.
A continuing state or habit (very common with jobs, occupations, and repeated actions)
- 兄はコンビニでアルバイトをしています。
  = My brother works at a convenience store / has a part-time job at a convenience store.

In your sentence, with no time word like 今, it is normally understood as a current ongoing situation / regular job, not just “this minute.”

Why is it しています instead of します?

します is the simple polite present/future: one-time or general action.

兄はコンビニでアルバイトをします。
Could sound like: “My brother will work at a convenience store (on that occasion / in the future).”

しています (the ている form) shows a current, ongoing state or regularly happening action, which is natural for talking about someone’s current job.

So アルバイトをしています is closer to “(currently) works / is working” than to “will work.”

Could I say 兄はコンビニでアルバイトです instead? What’s the difference?

You can say it, but the nuance changes:

兄はコンビニでアルバイトをしています。
Emphasizes the action: he is doing/works a part-time job at a convenience store.
兄はコンビニでアルバイトです。
Emphasizes the status/role: he is a part-time worker at a convenience store.

Both usually translate to something like “My older brother works part-time at a convenience store.”
The ～をしています version sounds more neutral and common in self-introductions or explanations about what someone does.

Is this sentence polite, casual, or formal?

しています is the polite form of している, so the sentence is in polite (です／ます) style.

Rough equivalents:

兄はコンビニでアルバイトをしている。 – casual
兄はコンビニでアルバイトをしています。 – polite (your sentence)
兄はコンビニでアルバイトをしております。 – very polite / humble (business-like)

Why isn’t there a word for “he” in the sentence?

Japanese usually omits pronouns when the subject is clear from context.

兄はコンビニでアルバイトをしています。
Literally: As for older brother, at a convenience store, is doing part-time job.

Once 兄 is stated as the topic with は, Japanese doesn’t repeat “he.” The verb form しています doesn’t change with person (I/you/he), so the subject is understood from context rather than a separate word like he.

Can the word order be changed, like 兄はアルバイトをコンビニでしています?

Yes, Japanese word order is relatively flexible as long as the verb comes at the end.

These are all grammatical:

兄はコンビニでアルバイトをしています。
兄はアルバイトをコンビニでしています。

The first is more typical and neutral. Changing the order can slightly change emphasis (e.g., focusing a bit more on アルバイト vs コンビニで), but the basic meaning remains the same.

What exactly does アルバイト mean? Is it just any job?

アルバイト (often shortened to バイト) means:

part-time job, especially for students or people who are not full-time employees.
Borrowed from German Arbeit (“work”).

It’s different from:

仕事 (しごと) – work/job in general (any kind of job).
正社員 (せいしゃいん) – full-time regular employee.

So コンビニでアルバイトをしています implies he’s a part-time worker, not necessarily a full-time staff member.

Could I write this sentence more “textbook-like” in hiragana/kanji?

A common way to write it with kanji is:

兄はコンビニでアルバイトをしています。 (already fine)
If you want more kanji:
兄はコンビニでアルバイトをしています。 – This is already the standard; アルバイト is usually in katakana.

You might see:

兄はコンビニでバイトをしています。 – using the casual short form バイト.