Contractul de închiriere este în sertar.

Because -ul is the Romanian definite article attached to the end of the noun.

• contract = a contract
• contractul = the contract

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

So:

• Contractul de închiriere = the rental contract / the lease agreement

De închiriere means something like for renting / rental.

The structure noun + de + noun is very common in Romanian and often works like an English descriptive phrase.

Here:

• contract = contract
• închiriere = renting, rental
• contract de închiriere = rental contract / lease agreement

Literally, it is close to contract of renting, but in natural English you would usually say rental contract or lease agreement.

Romanian often uses a noun phrase where English might use an adjective.

So instead of something exactly parallel to rental contract, Romanian commonly says:

• contract de închiriere

with închiriere as a noun meaning rental / renting.

This is a very normal pattern in Romanian:

• sală de clasă = classroom
• mașină de spălat = washing machine
• contract de muncă = employment contract

So de + noun is a very common way to describe what something is for or what type it is.

This is a very common question for English speakers.

Romanian does not always use the definite article where English uses the. After prepositions like în (in), an indefinite-looking noun can still refer to a specific place depending on context.

So:

• în sertar = in the drawer or in a drawer, depending on context
• în sertarul is possible, but it usually needs more information after it, such as:
  • în sertarul biroului = in the desk drawer
  • în sertarul de sus = in the top drawer

In your sentence, în sertar is the natural way to say in the drawer.

Este is the 3rd person singular of a fi (to be), so it means is.

• Contractul de închiriere este în sertar. = The rental contract is in the drawer.

In everyday Romanian, e is a very common shorter form:

• Contractul de închiriere e în sertar.

Both are correct.

• este sounds a bit more full or careful
• e sounds more natural in casual speech

The letter î represents a Romanian vowel that does not exist exactly in English. It is a close central vowel, somewhat like saying a tight, central uh sound.

A rough guide:

• în ≈ a short, tight sound somewhat like uhn, but not exactly
• închiriere ≈ uhn-kee-ree-EH-reh, very approximately

A few pronunciation notes:

• ch before i or e sounds like k
  • so închiriere starts with în-ki-
• Romanian r is usually tapped or lightly rolled
• Romanian vowels are pronounced clearly; they do not reduce as much as in English

The basic order here is the most neutral one:

• Contractul de închiriere este în sertar.

This is the normal subject + verb + place order.

Romanian word order is fairly flexible, though, and you can move things for emphasis:

• În sertar este contractul de închiriere.
• Contractul de închiriere în sertar este. — grammatically possible in some poetic or marked contexts, but not the normal everyday order

So for everyday speech, stick with:

• Contractul de închiriere este în sertar.

In this sentence, contractul is the subject, so it is in the nominative.

• contractul = the contract

After the preposition în, sertar is in the accusative function.

• în sertar = in the drawer

However, for most Romanian nouns, the nominative and accusative forms are identical, so you do not see a visible change here.

That means:

• contractul looks the way it does because it is definite
• sertar stays sertar after în

Yes, in most contexts it is.

Depending on context, contract de închiriere can be translated as:

• rental contract
• lease agreement
• lease

The exact English choice depends on the legal or everyday context, but the Romanian phrase is completely standard for a contract related to renting property or something else.

Because Romanian handles definiteness differently from English.

English requires:

• The contract is in the drawer.

Romanian can express the same idea with:

• Contractul ... în sertar.

Romanian is often less strict than English about marking definiteness after prepositions, especially when the context already makes the location clear.

So even though sertar has no visible definite ending here, the whole sentence can still naturally mean:

• The rental contract is in the drawer.

That is one of the places where Romanian and English do not match word-for-word.