Puer fessus est, tamen libros legit.

Puer is in the nominative singular, which is the case normally used for the subject of a clause. It means boy, and it is the person doing or being described in both parts of the sentence.

In this sentence:

• puer fessus est = the boy is tired
• libros legit = he reads books

Latin often leaves out a separate word for he, because the verb ending already shows the subject.

Fessus is an adjective and it must agree with puer.

Since puer is:

• masculine
• singular
• nominative

the adjective must also be:

• masculine
• singular
• nominative

So we get fessus.

If the subject were feminine, you would expect fessa. If it were plural masculine, you would expect fessi.

Est is the 3rd person singular present of esse, meaning to be.

So puer fessus est literally means the boy tired is, or more naturally, the boy is tired.

Latin sometimes omits forms of to be in poetry or later styles, but in normal prose est is usually expressed.

Legit is:

• 3rd person singular
• present tense
• active voice
• from legere = to read

So it means he/she/it reads.

Because it is 3rd person singular, it matches puer.

Latin usually does not need to state subject pronouns like he, she, or they, because the verb ending already tells you the person and number.

So legit by itself already means he/she reads.

Since puer has already been mentioned, the reader naturally understands that legit still refers to the boy.

Libros is the accusative plural of liber, meaning book.

The accusative case is used for the direct object, the thing being read.

So:

• legit libros = he reads books

Why plural? Because libros means books, not a book or the book.

Tamen means however, nevertheless, or still.

It shows contrast:

• Puer fessus est = the boy is tired
• tamen libros legit = nevertheless, he reads books

So the idea is: even though he is tired, he still reads.

They are similar, but not identical.

• sed usually means but
• tamen usually means however / nevertheless / still

In this sentence, tamen emphasizes that the second idea happens despite the first one. That makes the contrast a bit stronger.

So tamen fits well with the sense he is tired, yet he reads.

Latin word order is more flexible than English word order because the endings show the grammatical roles.

So Puer fessus est, tamen libros legit is a normal order, but other orders are possible, such as:

• Fessus est puer, tamen libros legit
• Puer libros legit, tamen fessus est
  if you wanted a different emphasis

The basic meaning stays the same, though the emphasis may shift.

That is just a natural Latin arrangement. Latin often puts the subject first and then gives the description or action.

So:

• puer = subject first
• fessus est = what the boy is

But Latin could also say puer est fessus or fessus puer est in different contexts. The endings matter more than the position.

Classical Latin has no articles.

So puer can mean:

• the boy
• a boy

and libros can mean:

• the books
• books

You decide from context which English translation sounds best.

Yes. The Latin present tense often covers both ideas.

So legit can mean:

• he reads
• he is reading

Context tells you which English version is better.

In a simple sentence like this, reads is often the most straightforward translation, but is reading is also possible depending on context.

The sentence has two clauses:

1. Puer fessus est
2. tamen libros legit

The second clause does not repeat the subject puer, because it is understood from the first clause and from the verb ending -t in legit.

So the whole structure is basically:

• The boy is tired
• nevertheless, he reads books

That is a very common Latin way to avoid repeating words unnecessarily.