Nimeni nu fură cartea.

This is because Romanian uses negative concord.
When you use a negative word like nimeni (nobody / no one), the verb is also normally negated with nu.

So Romanian says:

Nimeni nu fură cartea.

Literally, it looks like Nobody does not steal the book, but grammatically it simply means Nobody steals the book.

Without nu, the sentence would be ungrammatical in standard Romanian.

Nimeni is a negative pronoun meaning nobody or no one.

A few useful things about it:

• It is used for people, not things.
• It is grammatically treated as singular.
• That is why the verb is in the 3rd person singular form here.

Compare:

• nimeni = nobody
• nimic = nothing

So if you are talking about people, nimeni is the correct word.

Fură comes from the verb a fura, meaning to steal.

Here it is in the present indicative, 3rd person singular, to match nimeni:

• eu fur = I steal
• tu furi = you steal
• el/ea fură = he/she steals
• noi furăm = we steal
• voi furați = you all steal
• ei/ele fură = they steal

Because nimeni is grammatically singular, Romanian uses the singular agreement:

Nimeni nu fură...

One small detail: fură is also the form for they steal, so the subject tells you whether it is singular or plural.

Because cartea means the book, while carte means book or a book.

Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

So:

• carte = book / a book
• cartea = the book

That ending -a is the definite article here.

Yes, functionally it is.

Instead of saying a separate word before the noun, Romanian often attaches the definite article to the noun itself.

So:

• English: the book
• Romanian: cartea

This is a very common Romanian pattern:

• băiat = boy

• băiatul = the boy

• fată = girl
• fata = the girl

So in cartea, the noun and the definite article are combined into one word.

Because pe is not normally used with ordinary inanimate direct objects like cartea.

In Romanian, pe often marks a direct object when that object is:

• a person
• a pronoun
• or something especially specific in certain contexts

For example:

• Văd cartea. = I see the book.
• Îl văd pe băiat. = I see the boy.

Since cartea is an inanimate noun, no pe is needed here.

Romanian word order is fairly flexible, although this sentence uses the most neutral, straightforward order:

Nimeni nu fură cartea.

That is a normal pattern: subject + nu + verb + object

Other orders are possible for emphasis, but they may sound less neutral. For example, Romanian can move things around to highlight the object or the subject.

So this version is the best one to learn as the basic pattern.

The letter ă is a very common Romanian vowel. It is pronounced like a short, relaxed uh sound, similar to the a in English sofa.

So fură sounds roughly like FOO-ruh, with the last vowel reduced.

A few learners' notes:

• a and ă are different letters in Romanian
• ă is not silent
• it appears very often in verb endings and other common words

It can depend on context.

The Romanian present tense often covers both:

• a general statement: Nobody steals the book
• something happening now: Nobody is stealing the book

If the speaker wants to make right now clearer, they can add a time word such as acum:

• Nimeni nu fură cartea acum. = Nobody is stealing the book now.

So the present tense in Romanian is a bit broader than the English simple present.

Yes, that is possible.

Nu fură nimeni cartea is still grammatical and still means Nobody steals the book. The difference is mainly one of emphasis or information structure.

• Nimeni nu fură cartea. = neutral, basic statement
• Nu fură nimeni cartea. = can sound more like Nobody is stealing the book, with extra focus on the negation or on nimeni

So the original sentence is the most neutral textbook version, but Romanian does allow variation.