Miles in regione aliena manet.

No. miles is singular, not plural.

It is the nominative singular form of miles, militis, meaning soldier.
For an English speaker, the -s ending can look plural, because English often uses -s for plurals, but Latin does not work that way.

So here:

• miles = the soldier / a soldier
• not soldiers

Its plural nominative would be milites.

miles is in the nominative case, which is the case normally used for the subject of the sentence.

In Miles in regione aliena manet, the verb is manet = remains / stays.
The person or thing doing that action is the soldier, so miles is the subject.

A very literal grammatical breakdown is:

• miles = subject
• manet = verb
• in regione aliena = prepositional phrase telling where

Because the preposition in can take different cases depending on the meaning.

Here it means in or within a place, showing location, so it takes the ablative.

That is why we get:

• in regione aliena = in a foreign region

If in meant motion into a place, Latin would usually use the accusative instead.

So:

• in + ablative = in / on somewhere
• in + accusative = into / onto somewhere

regione is the ablative singular of regio, regionis, a feminine noun meaning region, district, or area.

Its dictionary form is:

• regio, regionis (f.)

In this sentence, it is ablative because it follows in in the sense of location.

So:

• regio = nominative singular
• regione = ablative singular

Because aliena is an adjective modifying regione, and Latin adjectives must agree with the nouns they describe.

Since regione is:

• feminine
• singular
• ablative

the adjective must also be:

• feminine
• singular
• ablative

So we get:

• regione aliena = in a foreign region

The adjective comes from alienus, aliena, alienum, meaning foreign, belonging to another, or sometimes strange.

It can mean several related things, depending on context.

alienus often has the basic idea of belonging to another or not one’s own. From that, it can mean:

• foreign
• another person’s
• strange or unfamiliar

In regione aliena, the most natural meaning is foreign or unfamiliar:

• in a foreign region
• in an чужой / alien area in the broad sense

So yes, the word has a wider range than just one English word.

manet is:

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

It comes from the verb maneo, manere, meaning remain, stay, or continue to be.

So manet means:

• he/she/it remains
• he/she/it stays

Since the subject is miles, the sentence means:

• the soldier stays
• the soldier remains

Classical Latin has no articles like English the or a/an.

So miles can mean:

• a soldier
• the soldier

and regione aliena can mean:

• in a foreign region
• in the foreign region

Which one sounds best depends on context.
Latin often leaves that to the reader or listener.

Yes, the words could be rearranged, because Latin word order is more flexible than English word order.

This sentence is:

• Miles in regione aliena manet.

But Latin could also say things like:

• In regione aliena miles manet.
• Miles manet in regione aliena.
• In aliena regione miles manet.

All of these would still mean roughly the same thing, because the endings show the grammar.

That said, word order can change emphasis:

• putting in regione aliena first may emphasize the setting
• putting manet at the end is very natural in Latin

Both orders are possible in Latin.

So both of these are grammatical:

• regione aliena
• aliena regione

Latin adjectives do not have to come before the noun the way English adjectives usually do.

The choice often depends on style, emphasis, rhythm, or author preference.
In a simple learning sentence like this, regione aliena is just a straightforward noun + adjective order.

By itself, miles means soldier. Because it is singular, the verb manet is translated as he/she remains, but the noun itself is still soldier.

In normal English translation, you would usually say:

• The soldier remains in a foreign region or
• The soldier stays in a foreign region

If later sentences continued without repeating miles, Latin might then use the verb alone and English might translate with he.

A good vocabulary breakdown is:

• miles, militis (m.) = soldier
• in = in, on; into, onto depending on case
• regio, regionis (f.) = region, district, area
• alienus, aliena, alienum = foreign, another’s, strange
• maneo, manere, mansi, mansum = remain, stay

This is useful because Latin dictionaries usually list nouns and verbs by their full dictionary forms, not by the exact form you see in the sentence.