Puer tridentem et nassam ad litus portat.

Latin usually does not have words for the and a/an the way English does. A noun like puer can mean:

• boy
• a boy
• the boy

The context tells you which is most natural. So Puer tridentem et nassam ad litus portat can be understood as The boy carries the trident and the net/trap to the shore (or A boy..., depending on context).

Because puer is in the nominative case, which is the case normally used for the subject of the sentence.

Here the forms help you:

• puer = nominative singular → the boy (subject)
• tridentem = accusative singular
• nassam = accusative singular

So the sentence structure is telling you that the boy is doing the action, and the trident and the net/trap are receiving the action.

They are both direct objects, so they are both in the accusative case, but they belong to different declensions, so their accusative singular endings are different.

• tridens, tridentis → accusative singular tridentem
• nassa, nassae → accusative singular nassam

So the case is the same, but the noun patterns are different.

Yes. Here tridentem et nassam are two direct objects joined by et (and).

The verb portat means he/she carries, and the boy is carrying two things:

• tridentem = the trident
• nassam = the net/trap

English does the same thing: The boy carries the trident and the net.

Ad litus means to the shore or toward the shore.

• ad = to, toward
• litus = shore

This phrase shows the destination of the action. The boy is carrying the things to the shore.

Because litus is a neuter third-declension noun.

Its dictionary form is:

• litus, litoris = shore

For many neuter nouns in Latin, the nominative singular and accusative singular are the same. So:

• nominative singular: litus
• accusative singular: litus

Since ad takes the accusative when it means motion toward, ad litus is correct.

In Latin, ad is followed by the accusative case. Its basic idea is movement to or toward something.

So:

• ad litus = to the shore

This is a very common pattern in Latin:

• ad urbem = to the city
• ad villam = to the house/farmhouse
• ad flumen = to the river

Portat is:

• 3rd person singular
• present tense
• active voice
• indicative mood

It comes from porto, portare, meaning to carry.

So portat means:

• he carries
• she carries
• it carries

In this sentence, since the subject is puer (boy), it means he carries.

Both the subject and the verb are singular:

• puer = boy (singular)
• portat = he/she/it carries (singular)

If it were plural, you would expect forms like:

• pueri = boys
• portant = they carry

So the sentence clearly refers to one boy carrying the objects.

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

Its dictionary form is:

• puer, pueri = boy

This is perfectly normal in Latin. Other nouns do similar things, such as:

• ager, agri = field
• magister, magistri = teacher

So puer is still a second-declension masculine noun even though it does not end in -us.

Yes. Latin word order is much freer than English word order because the endings show the grammatical roles.

So these could all mean essentially the same thing:

• Puer tridentem et nassam ad litus portat.
• Ad litus puer tridentem et nassam portat.
• Tridentem et nassam puer ad litus portat.

Latin authors may change word order for emphasis, style, or rhythm. Even so, the most basic facts remain clear because of the case endings and the verb form.

In a sentence like this, yes. Et is the ordinary Latin word for and.

So:

• tridentem et nassam = the trident and the net/trap

It simply joins the two direct objects.

Because the verb ending already tells you the person and number.

• portat = he/she/it carries

So Latin does not need to say is portat or another pronoun here. The subject can still be stated if needed, and here it is:

• puer = the boy

That makes the sentence complete without any extra pronoun.

This sentence is a good example of how Latin mixes different noun patterns together:

• puer, pueri → 2nd declension, masculine
• tridens, tridentis → 3rd declension, masculine
• nassa, nassae → 1st declension, feminine
• litus, litoris → 3rd declension, neuter
• porto, portare → 1st conjugation verb

So one short sentence already shows several major Latin patterns at once.

No. They are related, but not the same.

• ad litus = to the shore, toward the shore
  This suggests movement toward a destination.
• in litore = on the shore or at the shore
  This suggests location, not motion toward it.

So in this sentence, ad litus is used because the boy is carrying the items to the shore.