Můj bratr říká, že ho také bolí jeden zub a že musí jít k zubaři.

Czech does not have articles. That means nouns like bratr, zub, and zubař appear without any separate word for a/an or the.

So:

• Můj bratr = my brother
• jeden zub = literally one tooth, and in context often works like a tooth
• k zubaři = to the dentist

Czech relies on context much more than English does.

Because můj has to agree with bratr.

Bratr is:

• masculine
• singular
• animate
• nominative

So the correct possessive form is můj.

Compare:

• můj bratr = my brother
• moje sestra = my sister
• moje auto = my car

So the form of my changes depending on the noun it goes with.

Říká is the 3rd person singular present tense of říkat, meaning to say / to tell.

So:

• já říkám = I say
• ty říkáš = you say
• on/ona říká = he/she says

In this sentence, říká matches můj bratr, so it means my brother says.

Že means that and introduces a subordinate clause.

So:

• Můj bratr říká, že... = My brother says that...

It works like English that in reported speech.

In this sentence, everything after že is part of what the brother says.

Because there are two separate subordinate clauses, both depending on říká:

1. že ho také bolí jeden zub
2. že musí jít k zubaři

So the structure is:

• My brother says that X and that Y

In English, the second that is often optional. In Czech, repeating že is very common and often sounds clearer and more natural.

You may sometimes see the second že omitted, but repeating it is standard and helpful.

Because ho is not the subject here. It is the pronoun for him, and with bolet the person who feels pain is expressed as an object-like form.

So Czech says something like:

• ho bolí zub
• literally: a tooth hurts him

That is why you use ho, not on.

• on = he
• ho = him

This is a very common pattern with bolet:

• Bolí mě hlava. = My head hurts. / My head is hurting.
• Bolí ho zub. = His tooth hurts. / A tooth hurts him.

The grammatical subject is jeden zub.

That may feel unusual at first, because English learners often focus on he as the main person in the sentence. But in Czech, with bolet, the thing that hurts is the subject:

• jeden zub = one tooth

And the person affected is ho = him.

So the logic is:

• One tooth hurts him.

That is why zub is in the nominative form.

Both are possible, but jeden zub emphasizes that it is one single tooth.

Compare:

• Bolí ho zub. = His tooth hurts. / A tooth hurts him.
• Bolí ho jeden zub. = One tooth hurts too. / He also has one tooth that hurts.

Using jeden helps highlight the number: not several teeth, just one.

So here it adds a small nuance of one particular tooth or just one tooth.

Czech often leaves out subject pronouns when they are already clear from context.

So:

• že musí jít k zubaři = that he has to go to the dentist

There is no need to say on because the subject is already understood to be my brother.

Including on is possible, but it usually adds emphasis or contrast:

• že on musí jít k zubaři = that he has to go to the dentist (with extra stress on he)

Without emphasis, Czech normally omits the pronoun.

This is a very common modal construction:

• muset = must / have to
• jít = to go

So:

• musí jít = he must go / he has to go

The first verb is conjugated (musí), and the second stays in the infinitive (jít).

This works just like other Czech modal combinations:

• může přijít = he can come
• chce odejít = he wants to leave
• musí čekat = he has to wait

Because the preposition k takes the dative case and is used for movement to a person, especially a professional such as a doctor or dentist.

So:

• zubař = dentist
• k zubaři = to the dentist

This same pattern appears in:

• jdu k lékaři = I am going to the doctor
• jde k učiteli = he is going to the teacher
• jedeme k babičce = we are going to grandma's place

So the form zubaři is the dative singular of zubař.

Také means also or too.

In this sentence, it shows that the brother also has this problem:

• ho také bolí jeden zub = one tooth also hurts him / he also has a toothache

Its position is fairly natural here, but Czech word order is flexible. The exact position can slightly change emphasis.

You will also often hear the more colloquial form taky in everyday speech:

• také = more neutral/written
• taky = more conversational

Czech word order is much more flexible than English word order, but the version you have is a very natural neutral sentence.

For example, the part

• že ho také bolí jeden zub

could be rearranged in other ways, such as:

• že jeden zub ho také bolí
• že ho jeden zub také bolí

Those alternatives are possible, but they may shift the emphasis slightly.

So for a learner, the given version is a good standard model:

• Můj bratr říká, že ho také bolí jeden zub a že musí jít k zubaři.