Magistra horologium spectat et discipulos domum redire iubet.

Because magistra is in the nominative singular, which is the case usually used for the subject of a Latin sentence.

• magistra = the (female) teacher
• It is a first-declension noun, so the -a ending here is nominative singular.

So magistra is the person doing the actions:

• spectat = she looks at
• iubet = she orders

Because it is the direct object of spectat.

• spectat means looks at / watches
• The thing being looked at goes into the accusative case
• So horologium means clock or watch, and here it appears as horologium because it is a neuter second-declension noun, whose nominative and accusative singular are the same.

So:

• magistra horologium spectat = the teacher looks at the clock/watch

spectat is:

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

It comes from spectare = to look at, watch.

So spectat means:

• she looks at
• or he/she/it looks at

Here it must mean she looks at, because the subject is magistra.

Because discipulos is the direct object of iubet.

• discipulus = student, pupil (masculine)
• discipulos = students in the accusative plural

In Latin, iubere often works like this:

• someone
  • orders
• someone else
  • to do something

That someone else is put in the accusative.

So:

• discipulos ... iubet = she orders the students ...

Because after iubet, Latin commonly uses an accusative + infinitive pattern.

So instead of saying something like:

• she orders the students and they return home

Latin says:

• she orders the students to return home

That is why you get:

• discipulos domum redire iubet

Here:

• discipulos = the people being ordered
• redire = to return
• iubet = orders

So redire is not the main verb of the sentence. It is part of the idea of what she orders them to do.

iubet comes from iubere, meaning to order, command.

In this sentence it has:

1. a direct object: discipulos
2. an infinitive telling what they are ordered to do: redire

So the structure is:

• magistra = subject
• discipulos = the people ordered
• redire = what they are told to do
• iubet = orders

This is a very common Latin construction:

• aliquem facere aliquid iubere = to order someone to do something

Because domum is a special accusative used to show motion toward home.

With many places in Latin, especially home, towns, and small islands, Latin often does not use a preposition like ad.

So:

• domum = homeward / to home / home

Compare:

• domum ire = to go home
• domum redire = to return home

This is idiomatic Latin. English uses a similar idea when we say simply go home, not usually go to home.

redire means to go back, to return.

It comes from:

• re- = back
• ire = to go

So domum redire means:

• to return home
• to go back home

It is more specific than just ire (to go), because it includes the idea of going back.

Because one subject can easily govern more than one verb in Latin, just as in English.

Here the subject magistra does two actions:

1. horologium spectat = she looks at the clock
2. discipulos domum redire iubet = she orders the students to return home

The word et joins those two actions:

• looks at the clock and orders the students to return home

So Latin does not need to repeat magistra a second time.

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

For example, these would mean essentially the same thing:

• Magistra horologium spectat et discipulos domum redire iubet.
• Horologium magistra spectat et discipulos domum redire iubet.
• Magistra discipulos domum redire iubet et horologium spectat.

However, word order still affects emphasis and style.

The given order is quite natural:

• first the teacher looks at the clock,
• then she orders the students to go home.

So the sentence feels sequential and clear.

It can mean either, depending on context.

In many beginner Latin passages, horologium is often translated as:

• clock
• sometimes watch
• occasionally more generally timepiece

If the meaning has already been given as clock, that is probably the intended sense here. The important grammar point is that it is the object of spectat.

Because Latin usually expresses to do something with an infinitive alone, not with a separate word like English to plus a finite verb.

In English:

• she orders the students to return home

In Latin:

• discipulos domum redire iubet

The infinitive redire already contains the idea that English expresses with to return.

So there is no separate Latin word here corresponding exactly to English to.

Grammatically, discipulos is masculine plural, so literally it means male students or a mixed group if masculine is being used in the generic way.

If the writer wanted to refer specifically to girls, Latin would normally use:

• discipulas

If the context does not make gender important, many textbooks simply translate discipulos as the students.