Puer deorsum e turri spectat.

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

Also, the verb spectat is third person singular, so we expect a singular subject, and puer fits that perfectly.

Dictionary form:

• puer, pueri = boy

So puer is the boy as the subject.

Quite a lot. Spectat is from spectare, and its ending -t tells you it means:

• he looks
• she looks
• it looks

In this sentence, puer makes it clear that it means he looks.

So Latin does not need a separate word for he here. The verb ending already includes that information.

Not exactly.

• videt = sees
• spectat = looks at, watches, gazes at

So spectat suggests a more deliberate action of looking. That works especially well with deorsum, because the sentence is describing the direction in which the boy is looking.

Deorsum is an adverb. It means down, downward, or downwards.

It modifies the verb spectat, telling you how or in what direction the boy looks.

So it does not agree with any noun, and it does not change its form. It is just an indeclinable adverb.

Because e means out of or from, and it is used here to show the place from which the boy is looking.

So e turri means from the tower.

Even though the boy is not necessarily moving, Latin can still use e/ex + ablative to show the point of origin or viewpoint of an action.

E and ex are two forms of the same preposition.

In many texts:

• e is commonly used before a consonant
• ex is commonly used before a vowel or h

Since turri begins with a consonant, e turri is perfectly normal.

You may still sometimes see ex before consonants too, depending on the author or style. But here e turri is very standard.

Because e/ex takes the ablative case, and turri is the ablative singular of turris.

Dictionary form:

• turris, turris = tower

Important forms here:

• nominative singular: turris
• ablative singular: turri

So after e, Latin uses turri, not turris.

The phrase itself does not force one very precise picture. It simply gives the tower as the place from which he is looking.

Depending on context, that could mean:

• from a window in the tower
• from the top of the tower
• from some position in the tower

English often leaves this broad too when it says from the tower.

Yes, Latin word order is much more flexible than English word order.

This sentence could be rearranged in several ways without changing the basic meaning, for example:

• Puer e turri deorsum spectat
• Deorsum puer e turri spectat
• E turri puer deorsum spectat

The differences are mainly about emphasis or style, not the core meaning.

In the given sentence, putting deorsum early gives some prominence to the idea of looking downward.

It goes with spectat.

That is, the structure is basically:

• puer = subject
• spectat = verb
• deorsum = adverb modifying the verb
• e turri = prepositional phrase showing the place from which he looks

So the sense is the boy looks downward from the tower, not the downward tower or anything like that.