Pater adest et ianuam aperit, cum serva ianuam pulsat.

Latin does not have words for the or a/an. So pater can mean:

• father
• the father
• sometimes even a father

You decide which English article to use from the context. In this sentence, English naturally uses the father.

Adest is from the verb adsum, adesse, which literally means to be present, to be here, or to arrive / come up depending on context.

So pater adest can be understood as:

• the father is here
• the father arrives
• the father is present

It is different from plain est (is). The prefix ad- adds the idea of being at hand / present / here.

Because ianuam is the accusative singular form of ianua (door).

In Latin, the direct object of a verb usually goes in the accusative case. Here, the door is the thing being acted on:

• aperit ianuam = he opens the door
• serva ianuam pulsat = the slave woman/maid knocks on the door

So ianuam shows that door is the object in both parts of the sentence.

Because serva is the subject of pulsat, so it is in the nominative case.

Compare:

• serva = the female slave / maid as subject
• servam = the female slave / maid as direct object

In cum serva ianuam pulsat, the serva is the one doing the knocking, so nominative serva is correct.

It can mean any of those, depending on context.

Grammatically, serva is the feminine form of servus. A textbook might translate it as:

• female slave
• servant
• maid

The exact English word depends on the setting and the tone of the passage.

Here cum is a conjunction meaning when.

So:

• cum serva ianuam pulsat = when the maid knocks on the door

This is different from cum meaning with. When cum means with, it is a preposition and is followed by an ablative noun. That is not what is happening here.

Because this is a straightforward temporal clause: when the maid knocks on the door.

In simple sentences like this, Latin often uses cum + indicative for an ordinary when clause.

So:

• cum serva ianuam pulsat = when the maid knocks on the door

The subjunctive often appears with cum in more literary or more nuanced uses, such as circumstantial, causal, or concessive clauses. But here the clause is simple and direct, so the indicative is expected.

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

The verb ending already tells you the person and number:

• aperit = he/she/it opens
• pulsat = he/she/it knocks

Then the nominative nouns tell you who that he/she is:

• pater adest et ianuam aperit → pater is the subject of adest and aperit
• cum serva ianuam pulsat → serva is the subject of pulsat

So Latin relies on verb endings and case endings, not on always stating he or she.

Latin often repeats nouns where English would prefer a pronoun.

So Latin says:

• ianuam aperit ... ianuam pulsat

English usually prefers:

• he opens the door when the maid knocks on it

But Latin is perfectly happy to repeat ianuam. This repetition is normal and often clearer.

The word order is fairly flexible in Latin, because the endings show the grammar.

This sentence is:

• Pater adest et ianuam aperit, cum serva ianuam pulsat.

But Latin could rearrange many parts without changing the basic meaning, for example:

• Cum serva ianuam pulsat, pater adest et ianuam aperit.
• Pater et adest et ianuam aperit, cum serva ianuam pulsat.

That said, word order still affects emphasis, style, and flow. The given order is natural and easy to follow.

Pater is nominative singular, because it is the subject.

It belongs to the third declension, even though it may not look like a typical third-declension noun at first.

Its forms include:

• pater = nominative singular
• patris = genitive singular

So in this sentence, pater is the one who is present and opens the door.

Both ianua and serva are first-declension nouns.

Their nominative singular ends in -a:

• ianua = door
• serva = female slave / maid

Their accusative singular ends in -am:

• ianuam
• servam

That is why you see:

• serva as the subject
• ianuam as the object

They are simple present tense forms:

• adest = is here / arrives
• aperit = opens
• pulsat = knocks

In beginner Latin, these are often translated with the English simple present. Depending on context, English might also use a more natural form such as:

• The father comes and opens the door when the maid knocks.
• The father is here and opens the door when the maid knocks.

In a narrative, Latin often uses the present tense quite freely to describe events vividly.

Yes. Et is the ordinary Latin word for and.

Here it joins two actions with the same subject:

• pater adest
• et ianuam aperit

So the father both is present/arrives and opens the door.

Not in this sentence.

If cum meant with, then serva would have to be in the ablative. For a first-declension noun like serva, the ablative singular is also servā in spelling without macrons often written the same way, which can confuse learners.

But here the structure makes it clear that cum is a conjunction meaning when, because it introduces a clause with its own verb:

• cum serva ianuam pulsat

That whole section is a clause: when the maid knocks on the door.

Because there is no new nominative subject before aperit, and the sentence naturally continues with the same subject.

So:

• pater adest = the father is present / arrives
• et ianuam aperit = and opens the door

Latin often omits repeating the subject when it stays the same.

If the sentence wanted to make someone else the subject of aperit, it would usually name that new subject explicitly.

Yes. Latin often uses a direct object where English uses a preposition.

So Latin says:

• ianuam pulsat = literally knocks the door

But idiomatic English is:

• knocks on the door
• knocks at the door

This is a normal kind of difference between Latin and English verb usage.