Puella equitem videt.

Because equitem is the accusative singular form of eques. The accusative case is normally used for the direct object, the person or thing receiving the action.

So here:

• eques = horseman / cavalryman as a subject
• equitem = horseman / cavalryman as a direct object

Since the horseman is being seen, Latin uses equitem.

Latin shows this through case endings, not mainly through word order.

• puella = nominative = subject
• equitem = accusative = direct object

So the grammar tells us that the girl is doing the seeing, and the horseman is being seen.

Videt means he/she/it sees. It is third person singular.

It is not video because video means I see, which is first person singular.

Since puella means the girl, and she is third person singular, the verb must also be third person singular: videt.

Latin often puts the verb near or at the end, and that is a very common word order. So Puella equitem videt is perfectly natural.

However, Latin word order is more flexible than English because the endings already show each word’s job. For example, these can all mean the same basic thing:

• Puella equitem videt
• Puella videt equitem
• Equitem puella videt

The endings still show who is subject and who is object.

Classical Latin does not normally use articles like English the or a/an.

So puella can mean:

• the girl
• a girl

And equitem can mean:

• the horseman
• a horseman

Which one sounds best depends on context.

The dictionary forms are:

• puella — dictionary form already shown here
• eques — the base form behind equitem
• video — the base form behind videt

More fully, a dictionary might give:

• puella, puellae = girl
• eques, equitis = horseman / cavalryman
• video, videre = see

So when you look up equitem, you would need to know that its nominative form is eques.

• puella is a first-declension noun
• eques / equitem is a third-declension noun
• video / videt is a second-conjugation verb

This matters because Latin uses different sets of endings for different declensions and conjugations. Learning those patterns helps you recognize forms quickly.

Yes. Latin often leaves out a subject pronoun or even a subject noun when the verb already makes the person and number clear.

Videt already means he/she/it sees, so equitem videt could mean she sees the horseman if the context makes clear who she is.

But in Puella equitem videt, the noun puella is included to state explicitly who is doing the action.

In a classical-style pronunciation, it would be roughly:

• puella = poo-EL-la
• equitem = EH-kwi-tem
• videt = WI-det

So the whole sentence sounds roughly like:

poo-EL-la EH-kwi-tem WI-det

The stress is usually on -el- in puella, -qui- in equitem, and the first syllable of videt.