Avia servam monet ut pannum mundum ad mensam ferat.

Because servam is the direct object of monet. With moneo, monere, Latin often puts the person being advised, warned, or reminded in the accusative.

So here:

• avia = the grandmother, the subject
• servam = the maidservant, the person the grandmother is advising

Even though the maidservant is also the person who will do the bringing in the ut-clause, she still appears as the object of monet.

Because after a verb like monet, Latin commonly uses ut + the subjunctive to express an indirect command.

So:

• monet ut ... ferat = advises/warns that she should bring ...
• not a plain statement of fact

If Latin used fert, that would be an indicative statement, not the normal way to express this kind of command or advice.

Here ut introduces an indirect command.

After verbs of advising, ordering, asking, persuading, warning, and similar ideas, Latin often uses:

• ut
  • subjunctive

So servam monet ut pannum mundum ad mensam ferat means literally something like:

• the grandmother advises the maidservant that she should bring the clean cloth to the table

In smoother English, we usually say advises the maidservant to bring...

The subject of ferat is understood to be the maidservant, the same person referred to by servam.

Latin often leaves subjects unstated when they are clear from the context. So the sentence does not mean that the grandmother is doing the bringing. It means the grandmother is advising the maidservant, and the maidservant is the one who should bring the cloth.

Because mundum is an adjective modifying pannum, and adjectives agree with their nouns in:

• gender
• number
• case

Here:

• pannum = masculine singular accusative
• mundum = masculine singular accusative

So pannum mundum means the clean cloth.

Ad with the accusative usually means to or toward a place.

So:

• ad mensam = to the table

This fits the idea of movement with ferat.

If Latin wanted to describe location rather than motion, it would use something else, such as in mensa for on the table.

Avia is nominative singular because it is the subject of monet.

It is the one performing the action of advising. So:

• avia = subject
• servam = object
• monet = verb

Latin word order is much freer than English word order because the endings show how the words function.

This sentence is perfectly natural, but the basic meaning would stay the same if the words were rearranged, for example:

• Avia servam monet ut ad mensam pannum mundum ferat.
• Avia monet servam ut pannum mundum ad mensam ferat.

The chosen order keeps pannum mundum together and places the ut-clause neatly after monet.

Because the main verb monet is present, and Latin normally uses the present subjunctive in an indirect command when the action is viewed as happening at the same time as, or after, the main verb.

So the pattern is exactly what you would expect:

• monet = present indicative
• ferat = present subjunctive

This is standard sequence after a primary tense.

Because Latin and English do not always build sentences in the same way.

English says:

• The grandmother advises the maidservant to bring the clean cloth to the table.

But Latin usually expresses this idea with:

• monet
  • person
• ut
  • subjunctive

So instead of an infinitive like to bring, Latin prefers an indirect command: that she should bring.

It can mean any of those, depending on context. Moneo has a fairly broad range of meanings, including:

• warn
• advise
• remind
• sometimes instruct

In this sentence, the surrounding context makes something like advises or tells sound most natural in English. The exact shade depends on what tone you want the grandmother to have.