Amici figlinam intrant.

Because intrant means they enter, so the subject must be plural.
Amici is the nominative plural form of amicus (friend), so it fits as the subject: friends.

A native English speaker might notice that amici can also look like another form, but in this sentence the verb makes it clear that it means friends.

Figlinam is accusative singular.

It is the direct object of intrant, so it answers the question what do the friends enter?
They enter the figlina.

The ending -am is a very common sign of the accusative singular in a first-declension noun.

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

So:

• amici can mean friends or the friends
• figlinam can mean a pottery workshop or the pottery workshop

You understand the exact sense from the context.

Because Latin intrare can take a direct object.

So Latin can say:

• figlinam intrant = they enter the workshop

English often uses enter the same way too: They enter the building.
So this is not in figlinam here; figlinam is simply the object of the verb.

Intrant is:

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

It comes from intrare = to enter.

So intrant means they enter or they are entering, depending on context.

You would usually look them up as:

• amicus, -i = friend
• figlina, -ae = pottery workshop / brickworks / tileworks
• intro, intrare = enter

That is how Latin words are normally listed in dictionaries or vocabulary lists.

Amici comes from amicus, which is a second-declension masculine noun.

Its basic pattern includes forms like:

• amicus = friend
• amici = friends

Figlinam comes from figlina, which is a first-declension feminine noun.

Its pattern includes forms like:

• figlina = pottery workshop
• figlinam = pottery workshop (as direct object)

Yes. Latin word order is much more flexible than English word order because the endings show the grammar.

So these could all mean basically the same thing:

• Amici figlinam intrant
• Figlinam amici intrant
• Intrant amici figlinam

The difference is usually one of emphasis or style, not basic meaning.

By itself, amici could sometimes be ambiguous, because it can also be the genitive singular form of amicus in other contexts.

But here that does not fit the sentence well, because intrant needs a plural subject. So here amici is clearly nominative plural: friends.

A common classroom pronunciation would be roughly:

AH-mee-kee fig-LEE-nam IN-trahnt

More carefully:

• amici = ah-MEE-kee
• figlinam = fig-GLEE-nam or fee-GLEE-nam, depending on the pronunciation system being used
• intrant = IN-trahnt

Different Latin pronunciation systems exist, but the grammar stays the same.