September discipulos ad scholam revocat.

• September: the subject of the sentence, in the nominative singular
• discipulos: the direct object, in the accusative plural
• ad scholam: a prepositional phrase meaning to school, with ad
  • accusative
• revocat: the verb, meaning calls back / brings back

So the structure is basically:

September + the students + to school + calls back

Because it is the accusative plural of discipulus, meaning student or pupil.

A learner often memorizes:

• nominative singular: discipulus
• accusative singular: discipulum
• nominative plural: discipuli
• accusative plural: discipulos

Here the students are receiving the action of the verb revocat, so Latin puts them in the accusative case.

Because ad means to / toward, and it takes the accusative case.

So:

• ad scholam = to school
• in schola = in school / at school

The form scholam is the accusative singular of schola.

This is a very common Latin pattern:

• ad villam = to the house/farm
• ad urbem = to the city
• ad scholam = to school

The ending -t tells you the verb is third person singular in the present tense.

So:

• revoco = I call back
• revocas = you call back
• revocat = he/she/it calls back

Its dictionary form is revoco, revocare, a first-conjugation verb.

In this sentence, the subject is September, which is singular, so the verb is singular too: revocat.

The prefix re- usually adds the idea of back or again.

• vocat = calls
• revocat = calls back / recalls / brings back

So revocat is stronger and more specific than vocat. It suggests that the students had been away and are now being brought back again.

Yes. In this sentence, September is treated as the thing that brings the students back to school.

This is a kind of personification, and English does something similar:

• Spring brings flowers
• Winter drives people indoors
• September sends children back to school

So even though September is a month, Latin can still use it as the grammatical subject.

Because Latin has no articles like English the or a/an.

Latin simply says:

• discipulos = students / the students
• scholam = school / the school

English has to choose whether to say the students, students, a school, or the school, depending on context. Latin leaves that to the reader or translator.

Yes, it could be different. Latin word order is much more flexible than English word order because the case endings show what each noun is doing.

This sentence could also appear as:

• September ad scholam discipulos revocat
• Discipulos September ad scholam revocat
• Ad scholam discipulos September revocat

All of these still mean basically the same thing, though the emphasis may shift.

The given order is very natural for a learner:

• subject first
• object next
• prepositional phrase
• verb last

Also, Latin often likes to put the verb at the end.

It does decline. September is a real Latin noun, not an indeclinable foreign word.

Its genitive is Septembris, so it belongs to the third declension.

In this sentence, it is nominative singular because it is the subject:

• September = September
• Septembris = of September

So the form here is exactly the one you would expect for a singular subject.

In a common Classical-style pronunciation, you could say it roughly like this:

• September = seh-TEM-ber
• discipulos = dee-skee-POO-los
• ad scholam = ad SKO-lam
• revocat = reh-wo-KAT

A few helpful points:

• c is always hard, like k
• v is often pronounced like w in Classical Latin
• sch is pronounced like sk

So the whole sentence is roughly:

seh-TEM-ber dee-skee-POO-los ad SKO-lam reh-wo-KAT