Magistra dicit bonam disciplinam non tam severam esse quam utilem.

It uses a very common Latin pattern after a verb of saying:

• Magistra dicit = The teacher says
• bonam disciplinam ... esse = that good discipline is ...

This is called an indirect statement in Latin.
Instead of using that plus a finite verb, Latin normally uses:

• an accusative noun as the subject of the reported statement
• an infinitive as the verb

So bonam disciplinam ... esse means that good discipline is ...

Because in an indirect statement, Latin puts the subject of the reported idea into the accusative.

So in English we say:

• The teacher says that good discipline is useful.

But in Latin, the part meaning good discipline is useful becomes:

• bonam disciplinam utilem esse

Here:

• disciplinam is accusative singular
• it is still the logical subject of esse

This feels strange to English speakers, because English keeps good discipline as the subject, but Latin changes its case inside indirect statement.

Esse is the infinitive of sum, meaning to be.

Since dicit introduces an indirect statement, Latin does not use a normal finite verb like est. Instead, it uses the infinitive:

• est = is
• esse = to be

So:

• bonam disciplinam severam esse = that good discipline is strict

In this sentence, esse belongs to both adjectives in the comparison:

• non tam severam esse quam utilem
• to be not so much strict as useful

The second esse is simply left understood.

Non tam ... quam ... means:

• not so ... as ...
• or more naturally in many contexts, not so much ... as ...

So:

• non tam severam esse quam utilem

means:

• to be not so strict as useful
• or to be not so much strict as useful

The point is not that discipline is not strict at all, but that usefulness is the more important quality being emphasized.

Because they all agree with disciplinam.

Since disciplinam is:

• feminine
• singular
• accusative

the adjectives describing it must also be:

• feminine
• singular
• accusative

So:

• bonam disciplinam = good discipline
• severam = strict (agreeing with disciplinam)
• utilem = useful (also agreeing with disciplinam)

This is true even though severam and utilem come after esse in meaning. Latin still makes predicate adjectives agree with the noun.

Because utilis, utile is a third-declension adjective, not a first/second-declension one.

Its feminine accusative singular form is:

• utilem

Compare:

• bona, bonam from bonus, -a, -um
• severa, severam from severus, -a, -um
• utilis, utilem from utilis, utile

So even though disciplinam is feminine, the adjective does not become utilam, because that is not how this adjective declines.

No. Bonam goes directly with disciplinam:

• bonam disciplinam = good discipline

The comparison is between the two predicate adjectives:

• severam
• utilem

So the structure is basically:

• The teacher says [good discipline] [is not so much strict as useful].

In other words, the sentence is not comparing good discipline with something else. It is comparing two qualities of that discipline.

Latin often leaves out words that are easily understood from the context.

So:

• non tam severam esse quam utilem

literally has only one esse, but the sense is:

• non tam severam esse quam utilem esse

Latin does this very often in comparisons and parallel expressions. English does something similar:

• She is more kind than clever instead of
• She is more kind than she is clever

So the missing esse is understood.

Here quam is a conjunction of comparison, meaning than or as in the pattern non tam ... quam ...

So:

• non tam severam ... quam utilem
• not so strict ... as useful

It connects the two compared adjectives.

This is different from quam used as a relative adverb in other kinds of sentences.

• magistra is nominative singular: the teacher
• dicit is third person singular present active of dico: says

So:

• Magistra dicit = The teacher says

Then everything after that forms what she says.

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

For example, the sentence could be rearranged in several ways without changing the basic meaning, such as:

• Magistra bonam disciplinam non tam severam quam utilem esse dicit.
• Bonam disciplinam magistra non tam severam esse quam utilem dicit.

The original order is perfectly normal, but Latin often moves words around for emphasis, rhythm, or style.

In the given sentence, the order lets the reader hear:

1. who is speaking — Magistra
2. the reporting verb — dicit
3. the reported statement — bonam disciplinam ... esse
4. the comparison — non tam severam ... quam utilem

A very useful reading habit is this:

After a verb like dicit, putat, scit, audit, videt, look for:

1. an accusative noun or pronoun
2. an infinitive

Here you get exactly that:

• dicit
• bonam disciplinam = accusative
• esse = infinitive

That combination strongly signals:

• she says that ...

So when you see accusative + infinitive after a verb of saying or thinking, you should suspect an indirect statement right away.