Magistra discipulis narrat de mari.

Because magistra is in the nominative singular, the case normally used for the subject.

• magistra = teacher (female), as the person doing the action
• The verb narrat is third person singular, so it matches a singular subject: she tells / is telling

So magistra is the one who is telling.

Magistra means female teacher or mistress / instructress in some contexts.

It is feminine because it is the feminine form of magister.

• magister = male teacher
• magistra = female teacher

So this sentence specifically refers to a woman as the teacher.

Because discipulis is not in the nominative case. It is in the dative plural.

The dative often marks the indirect object, especially with verbs like narrat when someone is told something.

So here:

• magistra = the teacher
• discipulis = to the students

That is why discipulis means the people receiving the narration, not the ones doing it.

Because Latin often uses the dative for the person to whom something is told, given, shown, or said.

With narro, narrare (to tell, relate, narrate), the person being told is commonly put in the dative.

So:

• discipulis = to the students
• singular would be discipulo = to the student
• plural is discipulis = to the students

This is a very common Latin pattern.

Narrat is:

• present tense
• active voice
• indicative mood
• third person singular

From the verb narro, narrare = to tell, relate, narrate

So narrat means:

• she tells
• she is telling

In a simple sentence like this, English may translate it either way depending on context.

Because the preposition de means about or concerning, and after de Latin uses the ablative case.

The noun is:

• mare = sea in the nominative/accusative singular
• mari = sea in the ablative singular

So:

• de mari = about the sea

You cannot use de mare here, because de requires the ablative.

Because mare is a third-declension neuter noun, and its forms change depending on case.

Its singular forms include:

• mare = nominative
• maris = genitive
• mari = dative or ablative

Since de takes the ablative, Latin uses mari.

So de mari is grammatically the correct way to say about the sea.

The basic dictionary form is discipulus, discipuli, meaning student or pupil.

In this sentence, discipulis is the dative plural form.

So the pattern is:

• discipulus = student
• discipuli = students / of the student, depending on context
• discipulis = to/for the students

Here it means to the students.

Yes, the words could be arranged differently and still mean basically the same thing, because Latin relies more on word endings than English does.

For example, these could also work:

• Magistra de mari discipulis narrat.
• Discipulis magistra de mari narrat.
• De mari magistra discipulis narrat.

All still mean essentially The teacher tells the students about the sea.

However, word order can affect emphasis:

• putting de mari first may emphasize about the sea
• putting discipulis first may emphasize to the students

The given order is a normal, clear Latin sentence.

Latin has no definite article like English the, and no indefinite article like a/an either.

So:

• magistra can mean teacher or the teacher
• discipulis can mean to students or to the students
• de mari can mean about sea or, more naturally in English, about the sea

English has to add articles when translating, but Latin usually leaves them unstated unless context makes them clear.

Yes. Narro often takes both:

• a direct object = the thing being told
• a dative indirect object = the person told

For example:

• Magistra fabulam discipulis narrat.
• The teacher tells the students a story.

In your sentence, instead of a direct object, Latin uses de mari = about the sea.

So the idea is not she tells the sea, but she tells the students about the sea.

A common classroom pronunciation would be roughly:

mah-GIS-trah dis-key-POO-lees NAHR-raht deh MAH-ree

A more classical-style pronunciation would make c always hard, so discipulis sounds like:

dis-ki-POO-lis

A few helpful points:

• g in magistra is always hard, like in go
• c in Latin is always hard, like k
• r is usually trilled or tapped
• de is pronounced deh
• mari has two clear syllables after ma-: mah-ree

Because narrat is specifically the present tense form.

Compare:

• narrat = tells / is telling
• narravit = told / has told
• narrabit = will tell

So the tense is built into the verb ending. Latin verbs usually give a lot of information in one word.