Discipuli in bibliotheca melius discunt, quia ibi tacent.

Discipuli is the subject of the sentence.

• It is nominative plural
• It means students or pupils
• It comes from the dictionary form discipulus, -i meaning student

The ending -i here tells you it is plural and, in this sentence, the students are the ones doing the actions: discunt and tacent.

Because in can take different cases depending on the meaning.

• in + ablative = in / inside / at a place, showing location
• in + accusative = into a place, showing motion toward it

Here the sentence means the students are studying in the library, not moving into the library, so Latin uses the ablative:

• in bibliotheca = in the library
• in bibliothecam would mean into the library

So bibliotheca here is ablative singular.

Melius is the comparative adverb of bene.

• bene = well
• melius = better
• optime = best

So melius discunt means they learn better or they study better.

A native English speaker may expect something like more well, but Latin uses a special comparative form, just as English uses better instead of more well.

Discunt is a verb form meaning they learn or they study.

Its full parsing is:

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

It comes from disco, discere, didici = to learn

The ending -unt tells you the subject is they.

Tacent is also:

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

It comes from taceo, tacere, tacui = to be silent, to be quiet, or to keep quiet

So ibi tacent means they are quiet there or simply they keep quiet there.

Latin usually does not need to state subject pronouns unless they are being emphasized.

In English, we must say they learn and they are quiet.
In Latin, the verb endings already show who is doing the action:

• discunt = they learn
• tacent = they are quiet

So a separate they is unnecessary.

If Latin wanted to emphasize they, it could add ei or another pronoun in some contexts, but normally the verb ending is enough.

Quia means because and introduces a clause giving a reason.

So the sentence is built like this:

• Discipuli in bibliotheca melius discunt = The students study better in the library
• quia ibi tacent = because they are quiet there

The second part explains why they study better in the library.

They are related, but they do slightly different jobs.

• in bibliotheca specifically names the place: in the library
• ibi means there, referring back to that place

So the sentence works like this:

• in bibliotheca = tells you the location
• ibi = refers back to that location in the second clause

In natural English, we often do the same thing:

• Students study better in the library, because they are quiet there.

Latin is being very natural here.

No, Latin word order is much more flexible than English word order because the endings show the grammatical relationships.

This sentence has a very straightforward and natural order:

• Discipuli = subject
• in bibliotheca = place
• melius = adverb
• discunt = main verb
• quia = because
• ibi = there
• tacent = verb in the subordinate clause

But Latin could rearrange the words for emphasis, for example:

• In bibliotheca discipuli melius discunt, quia ibi tacent.
• Discipuli melius in bibliotheca discunt, quia ibi tacent.

These would still mean basically the same thing, though the emphasis might shift slightly.

It can reasonably be understood as either, depending on context.

The verb disco primarily means learn, but in many school-related contexts English may translate it as study.

So:

• discunt = learn
• or study

If the meaning already provided to the learner says study, that is perfectly natural in this sentence.

A helpful way to break it up is:

• Discipuli = the students
• in bibliotheca = in the library
• melius discunt = study better
• quia = because
• ibi tacent = they are quiet there

So the sentence has:

1. a main clause: Discipuli in bibliotheca melius discunt
2. a subordinate clause of reason: quia ibi tacent

That makes it a nice example of how Latin connects a main idea with an explanation.