Avia scribam vocat, ut testamentum novum scribat.

Because avia is in the nominative singular, which is the usual case for the subject, and vocat is 3rd person singular, so they fit together: the grandmother calls.

By contrast, scribam is in the accusative singular, so it works as the direct object of vocat.

Latin does not depend mainly on word order to show subject and object the way English does. The endings do that.

It can be, in other sentences. scribam is one of those Latin forms that can mean different things depending on context:

• scribam = I will write from scribere
• scribam = scribe / clerk in the accusative singular from scriba

Here it is clearly the noun, because:

• vocat naturally takes a direct object
• avia scribam vocat makes good sense as the grandmother calls the scribe

So this is a good example of why context matters in Latin.

Because declension and gender are not the same thing.

scriba is a masculine noun that belongs to the first declension. Latin has a number of masculine first-declension nouns, especially for occupations or social roles, such as:

• poeta = poet
• agricola = farmer
• nauta = sailor
• scriba = scribe

So scribam is a perfectly normal masculine accusative singular form, even though the ending may look feminine to a beginner.

They are two different words:

• scribam = a noun: the scribe in the accusative
• scribat = a verb: may write / should write / write in a purpose clause

They come from related forms:

• scriba = scribe
• scribere = to write

So Latin is using the same root scrib-, but in two different grammatical roles.

It introduces a purpose clause.

ut + subjunctive often means:

• so that
• in order that

So ut testamentum novum scribat tells us the purpose of calling the scribe.

The structure is:

• main clause: Avia scribam vocat
• purpose clause: ut testamentum novum scribat

Because after ut in a purpose clause, Latin normally uses the subjunctive.

So:

• scribit would be ordinary indicative: he writes
• scribat is subjunctive: that he may write / so that he may write

After a present-tense main verb like vocat, Latin commonly uses the present subjunctive in the purpose clause.

Most naturally, it is the scribe.

So the idea is: the grandmother calls the scribe so that he may write the new will.

Latin often leaves the subject of a verb unstated when it can be understood from context. There is no separate word here for he. The reader is expected to infer it.

Technically, Latin does not spell it out in this sentence, so context is what tells you that the writer is the scribe.

English often prefers a compact infinitive like to write, but Latin very often expresses purpose with ut + subjunctive.

So where English says:

• She calls a scribe to write a new will

Latin often says:

• She calls a scribe so that he may write a new will

That is a very normal Latin way to express purpose.

Because the adjective must agree with the noun in:

• gender
• number
• case

testamentum is:

• neuter
• singular
• accusative

So novum must also be:

• neuter
• singular
• accusative

That is why novus would be wrong here: novus is masculine nominative singular.

Yes. Both are possible.

Latin word order is much more flexible than English word order. The endings already show how the words fit together, so the adjective can come before or after the noun.

Both of these are grammatical:

• testamentum novum
• novum testamentum

A difference in word order may create a slight difference in emphasis, but not a basic change in meaning.

Because Classical Latin has no articles.

So Latin simply says:

• avia
• scribam
• testamentum novum

and the reader works out from context whether English should use:

• a
• an
• the
• or no article at all

That is why one Latin sentence can often be translated in more than one perfectly reasonable way in English.

Not nearly as much as it would in English.

This order is fairly straightforward:

• Avia = subject
• scribam = object
• vocat = verb
• ut ... scribat = purpose clause

But Latin could rearrange parts of the sentence for style or emphasis, and the case endings would still show who is doing what.

So in Latin, endings are usually more important than position.

vocat is:

• 3rd person singular
• present tense
• indicative
• active
• from vocare

So grammatically it means he/she/it calls.

Here, since the subject is avia, it means she calls. Depending on context, English might translate the present tense as either calls or is calling, but the basic Latin form is just the present indicative.