Filius vinum non bibit, sed aquam petit.

Because filius is the subject of the sentence: the son is the one doing the actions.

In Latin, the subject is usually put in the nominative case.
Filius is the nominative singular form of filius, filii meaning son.

So:

• filius = the son as subject
• if it were an object, it would be a different form, such as filium

They are both direct objects, so they are both in the accusative case. The endings are different because the nouns belong to different declensions.

• vinum is a 2nd declension neuter noun
• aqua is a 1st declension feminine noun

Their accusative singular forms are:

• vinum → vinum
• aqua → aquam

So the difference in ending does not mean they have different jobs in the sentence. They have the same job, but they come from different noun patterns.

Because vinum is a neuter noun of the 2nd declension. In Latin, neuter nouns have an important pattern:

• nominative singular = accusative singular

So:

• vinum can mean wine as a subject or as an object, depending on context

But aqua is not neuter; it is feminine, so its accusative singular is different:

• aqua → aquam

This is a very common Latin pattern and worth remembering.

Both are 3rd person singular, present tense, active, indicative verbs.

That means each one means he/she/it ...s in English.

So:

• bibit = he drinks, she drinks, or it drinks
• petit = he seeks/asks for/requests, depending on context

Because the subject is filius, we understand both as he:

• he does not drink
• he asks for / seeks

Latin does not need a helping verb like English do/does to make a negative sentence.

English says:

• He does not drink

Latin simply says:

• non bibit

Here:

• non = not
• bibit = he drinks

So non bibit literally means not drinks, but natural English translates it as does not drink.

Because non usually goes before the word or phrase it negates.

Here it negates the verb:

• non bibit = does not drink

That is the normal and expected placement. Latin word order is flexible, but non often appears directly before the verb or other word it is negating.

Sed means but.

It connects two contrasting ideas:

• Filius vinum non bibit = the son does not drink wine
• sed aquam petit = but he asks for water

So sed is a coordinating conjunction joining two clauses.

Because the subject is understood to stay the same.

Latin often avoids repeating a subject when it is already clear. In this sentence:

• Filius vinum non bibit
• sed aquam petit

The second verb, petit, is still 3rd person singular, so we naturally understand the same subject: the son.

In fuller Latin, you could repeat the noun, but it would usually be unnecessary.

Not always. Peto, petere has a range of meanings, such as:

• seek
• aim at
• head for
• ask for
• request

In this sentence, with aquam, the natural meaning is asks for water or possibly seeks water, depending on context.

This is very common in Latin: one verb can have several related meanings, and context tells you which one fits best.

Because Latin has no definite or indefinite article.

English distinguishes:

• the son
• a son

Latin usually just has:

• filius

The reader figures out whether it means the son, a son, or simply son from context.

The same is true for:

• vinum = wine / the wine
• aquam = water / the water

No. Latin word order is much more flexible than English word order because the endings show the grammatical roles.

In English, word order is crucial:

• The son drinks the wine is different from
• The wine drinks the son

In Latin, the noun endings help you tell subject from object, so the words can move around more freely.

For example, this sentence could be rearranged in several ways without changing the basic meaning, such as:

• Filius non bibit vinum, sed aquam petit.
• Vinum filius non bibit, sed aquam petit.

However, different word orders can change emphasis. The version you were given is a normal, clear way to say it.

Partly from meaning, and partly from structure.

The sentence has two balanced parts:

• vinum non bibit
• sed aquam petit

So each object naturally goes with the nearest verb:

• vinum with bibit
• aquam with petit

Latin can separate related words more than English can, but in a simple sentence like this, the grouping is quite straightforward.

They are:

• filius, filii = son
• vinum, vini = wine
• bibo, bibere = drink
• sed = but
• aqua, aquae = water
• peto, petere = seek, ask for
• non = not

For verbs, Latin dictionaries usually list the 1st person singular present and the infinitive, so:

• bibit comes from bibo, bibere
• petit comes from peto, petere

A common classroom pronunciation would be something like:

FEE-lee-oos WEE-noom non BEE-bit, sed AH-kwam PEH-tit

A few helpful points:

• c is always hard in classical pronunciation, though there is no c here except in aquam, where qu sounds like kw
• v in classical Latin is pronounced like w, so vinum sounds roughly like wee-num
• ti in petit is just ti, not sh

Pronunciation traditions vary, but this gives a good starting point.