Puer stilum supra mensam ponit.

Puer is the subject of the sentence, the one doing the action. It is in the nominative singular, which is the case Latin normally uses for the subject of a finite verb.

So:

• puer = the boy
• ponit = puts / places

Together, they give the boy puts/places.

Because puer is one of the masculine second-declension nouns that ends in -er in the nominative singular.

Its dictionary form is:

• puer, pueri = boy

Not every second-declension masculine noun ends in -us. Some end in -er, such as puer and ager. In puer, the e stays in the stem: pueri, puerum, and so on.

Stilum is in the accusative singular because it is the direct object of ponit.

It is the thing being put or placed.

The noun is:

• stilus, stili = pen / stylus / writing instrument

Its accusative singular is stilum.

So:

• puer = subject
• stilum = direct object

They are not doing the same job.

• stilum is the direct object of the verb.
• mensam is the noun governed by the preposition supra.

So mensam is not a second direct object. It is part of the prepositional phrase supra mensam.

This is very normal in Latin: you can have

• one accusative as the direct object, and
• another accusative after a preposition that requires the accusative.

Supra mensam is a prepositional phrase. It tells you the place or spatial relation connected with the action of ponit.

The important grammar point is:

• supra is a preposition
• it takes the accusative
• so mensa becomes mensam

So even if you already know the meaning, grammatically the phrase works as a unit: supra mensam.

Ponit is:

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

It comes from the verb:

• pono, ponere, posui, positum = put, place

The ending -it tells you he/she/it.

So ponit by itself means he places, she places, or it places. Since the subject here is puer, we understand the boy places.

Because Latin usually does not need an expressed subject pronoun unless it is being emphasized.

The verb ending already tells you the person and number:

• ponit = he/she/it puts

So Latin does not need to add a separate he. The noun puer makes the subject explicit anyway.

Latin does not have articles like English the and a/an.

So a noun like puer can mean:

• the boy
• a boy

And stilum can mean:

• the pen
• a pen

English has to choose one in translation, but Latin usually leaves that to context.

Here they are:

• puer, pueri — boy
• stilus, stili — pen / stylus
  
  • You may also see the spelling stylus
• supra — above / over; preposition taking the accusative
• mensa, mensae — table
• pono, ponere, posui, positum — put / place

Knowing the dictionary form helps you recognize why the word looks different in the sentence.

Because Latin often likes to place the verb near or at the end of the sentence, especially in simple textbook-style sentences.

A very literal order here is:

• Puer = boy
• stilum = pen
• supra mensam = above/on the table area
• ponit = puts

Latin word order is more flexible than English word order because the endings show each word’s job.

Yes, often it could.

For example, Latin could move words around for emphasis, style, or rhythm, as long as the case endings still make the roles clear. The core meaning would stay the same.

However, some arrangements sound more natural than others, and the phrase supra mensam will usually stay together as a phrase.

So Latin word order is flexible, but not random.

In a simple Classical Latin approximation, you could say it like this:

POO-er STIH-lum SOO-pra MEN-sam POH-nit

A few helpful points:

• puer has two syllables: pu-er
• c and g are not relevant here, but in Classical Latin they are always hard
• i in stilum is like the i in sit
• ponit is po-nit, not like English pony

A more important beginner goal than perfect pronunciation is just to say each ending clearly:

• puer
• stilum
• mensam
• ponit