Post pluviam serva mensam panno humido siccat.

Because of the rest of the sentence.

Here serva is a noun: nominative singular feminine, meaning female slave, servant, or maid. It is the subject of siccat: the servant dries.

A learner may notice that serva! can also be an imperative of servare meaning save! or preserve!. But that does not fit this sentence well, because we already have a finite verb, siccat = dries. Latin sentences normally do not need two unrelated main verbs like that without some clear connection.

So in this sentence:

• serva = subject noun
• siccat = main verb

Because it is in the nominative case, which is the case normally used for the subject.

In this sentence:

• serva = nominative singular → the servant/maid
• mensam = accusative singular → the table
• panno humido = ablative singular → with a damp cloth

Latin uses endings, not mainly word order, to show what each word is doing. So even though English depends heavily on position, Latin depends much more on case endings.

Because it is the direct object of siccat.

The verb siccare means to dry. The thing being dried is the direct object, so Latin puts it in the accusative:

• mensa = table as a dictionary form / nominative
• mensam = table as the direct object / accusative

So:

• serva mensam siccat = the servant dries the table

It is an ablative of means/instrument: it tells you by means of what or with what the action is done.

So:

• panno = with a cloth
• humido = damp, agreeing with panno

Together:

• panno humido = with a damp cloth

This is very common in Latin. When English uses with to show the tool or instrument, Latin often uses the ablative without a preposition.

Example pattern:

• gladio pugnat = he fights with a sword
• panno humido siccat = she dries with a damp cloth

Because humido is an adjective modifying panno, and Latin adjectives must agree with the nouns they describe in:

• gender
• number
• case

Here:

• panno is masculine, singular, ablative
• humido must also be masculine, singular, ablative

So panno humido means with a damp cloth.

Because the preposition post takes the accusative case when it means after.

So:

• pluvia = nominative / dictionary form
• pluviam = accusative, used after post

Therefore:

• post pluviam = after the rain

This is something you often just have to learn with each preposition: Latin prepositions usually require a specific case.

Literally it means after the rain.

Latin often uses a noun phrase where English might sometimes prefer a clause. So post pluviam is straightforwardly:

• post = after
• pluviam = rain

Depending on context, English might express the idea more naturally as:

• after the rain
• after it rains
• after the rainfall

But grammatically the Latin is a noun phrase: after the rain.

Siccat is present tense, third person singular, active voice.

Breakdown:

• verb: siccare = to dry
• stem: sicca-
• ending: -t = he/she/it

So siccat means:

• he dries
• she dries
• it dries

Here, because the subject is serva, it means she dries or the servant dries.

Because Latin word order is much more flexible than English, and putting the verb at or near the end is very common.

English usually prefers:

• The servant dries the table with a damp cloth after the rain.

Latin can do:

• Post pluviam serva mensam panno humido siccat.

This does not change the basic grammatical relationships, because those are shown by the endings:

• serva = subject
• mensam = object
• panno humido = instrument
• siccat = verb

So the final verb position is normal and often stylistically natural in Latin.

Yes, in many cases.

Because Latin marks function by case endings, you could rearrange this sentence in several ways without changing the core meaning. For example:

• Serva post pluviam mensam panno humido siccat.
• Mensam serva post pluviam panno humido siccat.
• Panno humido serva mensam post pluviam siccat.

All of these still mean essentially the same thing.

However, word order can affect emphasis. The original sentence may give a slight sense of setting the scene first with post pluviam and ending neatly with the action siccat.

Classical Latin does not have definite or indefinite articles like English the and a/an.

So:

• serva can mean a servant or the servant
• mensam can mean a table or the table
• panno humido can mean with a damp cloth or with the damp cloth

The context decides which English article sounds best. That is why translations can differ slightly even when the Latin is the same.

Yes. Pluvia is a feminine noun meaning rain.

In this sentence, it appears as pluviam because it follows post, which takes the accusative.

So:

• pluvia = rain
• post pluviam = after the rain

A learner may also meet related words like pluit = it is raining.

Because when Latin expresses the means or instrument used to do something, it often uses the bare ablative without cum.

So:

• panno humido = with a damp cloth

If you are thinking in English, it is tempting to expect a preposition because English usually needs with. Latin often does not.

Ablative without a preposition is especially common for:

• tools
• instruments
• means

So this construction is perfectly normal.

They are:

• post — preposition meaning after
• pluvia, pluviae — rain
• serva, servae — female slave / servant / maid
• mensa, mensae — table
• pannus, panni — cloth
• humidus, humida, humidum — damp, moist
• sicco, siccare, siccavi, siccatum — dry

This is useful because many words appear in an inflected form in the sentence:

• pluviam comes from pluvia
• mensam comes from mensa
• panno comes from pannus
• humido comes from humidus
• siccat comes from siccare

A good way to see it is:

• Post pluviam = time expression: after the rain
• serva = subject: the servant
• mensam = direct object: the table
• panno humido = means/instrument: with a damp cloth
• siccat = verb: dries

So the sentence is built like this:

After the rain, the servant dries the table with a damp cloth.

That is a very typical Latin pattern: time phrase + subject + object + ablative of means + verb.