Puella fidelis est, et magistra fidem eius laudat.

Because fidelis is a third-declension adjective, not a first-and-second-declension adjective like bona, bonus, bonum.

For many third-declension adjectives, the masculine and feminine nominative singular have the same form. So:

• fidelis puella = a faithful girl
• fidelis servus = a faithful slave

The neuter would be different:

• fidele

So fidelis agrees with puella in gender, number, and case, even though the ending is not the feminine -a that English speakers often expect at first.

Latin word order is much freer than English word order because the endings show how words function.

So puella fidelis est and fidelis puella est can both mean the girl is faithful.

In this sentence, putting fidelis after puella is completely normal. Adjectives in Latin can come before or after the nouns they describe. Sometimes word order adds emphasis or style, but often it is simply a natural Latin arrangement.

Est means is.

It links the subject puella with the description fidelis:

• puella = the girl
• fidelis = faithful
• est = is

So the structure is:

• Puella fidelis est = The girl is faithful

This is a very common Latin pattern:
subject + predicate adjective + est

Latin sometimes omits forms of to be, especially in poetry or very compact prose, but in normal beginner sentences it is often written out.

Because magistra is the subject of laudat.

The second clause is:

• et magistra fidem eius laudat

The verb laudat means praises, and the person doing the praising is the teacher. That makes magistra the subject, so it is in the nominative singular.

A helpful breakdown:

• magistra = the teacher (subject)
• fidem eius = her loyalty / faithfulness (direct object)
• laudat = praises

Because fidem is the direct object of laudat.

The dictionary form is fides, meaning faith, trust, loyalty, faithfulness. But in the sentence, the teacher is praising that loyalty, so the noun must be in the accusative singular:

• fides = nominative singular
• fidem = accusative singular

So:

• fides = loyalty / faithfulness
• magistra fidem laudat = the teacher praises the loyalty

This is a common pattern with verbs like laudat, which take a direct object in the accusative.

Eius means of him, of her, or of it.

It is the genitive singular form of is, ea, id. Here it modifies fidem, so literally it means:

• fidem eius = her loyalty / the loyalty of her

In smoother English, we usually say her loyalty.

So eius shows possession: the loyalty belongs to someone.

By context.

The form eius itself can mean:

• of him
• of her
• of it

It does not change form for masculine, feminine, and neuter in the singular genitive.

In this sentence, the obvious referent is puella, which is feminine and singular. So eius is understood as her:

• Puella fidelis est, et magistra fidem eius laudat.
• The girl is faithful, and the teacher praises her loyalty.

This is a very important Latin point.

Latin uses suus, sua, suum for a reflexive possessive, meaning a possession belonging to the subject of that clause.

But in this clause, the subject is magistra:

• magistra ... laudat = the teacher praises

So if Latin said fidem suam, it would normally mean:

• the teacher praises her own loyalty

That is not the meaning here. The loyalty belongs to the girl, not to the teacher. So Latin uses eius instead:

• fidem eius = her loyalty, meaning the girl’s loyalty

So the contrast is:

• suam = her own, referring back to the subject of the clause
• eius = his/her/its, referring to someone else

It can mean any of those, depending on context.

The noun fides has a broad range of meanings, including:

• faith
• trust
• reliability
• loyalty
• faithfulness

In this sentence, because puella fidelis est comes first, fidem eius is naturally understood as her faithfulness or her loyalty. The second clause matches the idea of the first clause:

• fidelis = faithful
• fidem = faithfulness / loyalty

So Latin is using a noun and an adjective from the same idea.

Because that is a very common Latin word order.

Latin often puts the verb last, especially in straightforward prose and textbook sentences. So:

• magistra fidem eius laudat

is a very natural Latin order:

• subject
• object
• verb

English usually prefers:

• subject
• verb
• object

So English says:

• The teacher praises her loyalty

But Latin often says:

• The teacher her loyalty praises

The meaning stays clear because the endings show the relationships between the words.

Yes, often it can.

Because Latin uses case endings, many rearrangements are possible without changing the basic meaning. For example:

• Puella fidelis est, et magistra fidem eius laudat.
• Puella est fidelis, et eius fidem magistra laudat.
• Et magistra eius fidem laudat.

These all still communicate the same basic idea.

However, word order can affect emphasis and style. For example:

• eius fidem may emphasize her loyalty
• placing laudat last gives a very typical Latin feel

So the endings keep the grammar clear, while the order can subtly shape the focus.