Rolul este interesant.

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

• rol = a role
• rolul = the role

Unlike English, Romanian usually puts the at the end of the noun instead of as a separate word.

So:

• Rolul este interesant. = The role is interesting.

Rolul is a noun. Its basic dictionary form is rol.

In this sentence:

• rolul = the subject
• este = the verb
• interesant = an adjective describing the subject

So the structure is:

• Rolul = subject
• este = is
• interesant = subject complement / adjective

Rol is a neuter noun in Romanian.

That can be confusing for English speakers, because Romanian neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

So in the singular:

• rol interesant
• rolul interesant

But in the plural:

• roluri interesante
• rolurile interesante

That is why interesant is in the masculine-looking singular form here.

Because the adjective has to agree with the noun in gender and number.

Here, rolul is singular, and as a neuter singular noun it takes the same adjective form as a masculine singular noun:

• masculine/neuter singular: interesant
• feminine singular: interesantă
• plural: interesante (for many common adjectives in this pattern)

So:

• rolul este interesant = the role is interesting
• cartea este interesantă = the book is interesting
• rolurile sunt interesante = the roles are interesting

Because here interesant is being used predicatively—it comes after este and describes the subject.

In Romanian, adjectives used this way normally do not take the definite article.

So:

• Rolul este interesant. = The role is interesting.

But when the adjective is placed with the noun inside the noun phrase, the structure can be different:

• rolul interesant = the interesting role

In your sentence, interesant is not part of the noun phrase rolul; it is the description after este.

Este is the 3rd person singular form of the verb a fi (to be) in the present tense.

So:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she is

Here it means is:

• Rolul este interesant. = The role is interesting.

In everyday speech, Romanians often use e instead of este:

• Rolul e interesant.

Both are correct. Este is a bit more formal or full.

Normally, no. In a standard sentence like this, Romanian usually keeps the verb to be.

So you say:

• Rolul este interesant.
• Rolul e interesant.

Not normally just:

• Rolul interesant. for The role is interesting

That shorter version would usually mean the interesting role, not a full sentence.

The neutral, most natural order is:

• Rolul este interesant.

Romanian word order is somewhat flexible, but changing it usually changes the emphasis.

For example:

• Interesant este rolul. = It is the role that is interesting / The role is what is interesting.

That sounds more marked or literary. For a basic statement, stick with:

• Rolul este interesant.

A simple English-friendly approximation is:

• ROH-lool YES-teh in-teh-reh-SAHNT

A few helpful notes:

• r is usually trilled or tapped
• o is a clear o, not a diphthong like in many English accents
• e in este is pronounced clearly
• final consonants are usually pronounced

A more careful breakdown:

• rolul → RO-lul
• este → YES-te
• interesant → in-te-re-SANT

Put nu before the verb:

• Rolul nu este interesant. = The role is not interesting.
• Rolul nu e interesant. = The role isn’t interesting.

So nu is the basic Romanian negation word for verbs.

In Romanian, a yes/no question is often made just by intonation in speech:

• Rolul este interesant? = Is the role interesting?

In writing, the word order can stay the same; the question mark shows it is a question.

You may also hear more marked patterns in speech, but for a learner, the simplest version is:

• Rolul este interesant?

The plural is:

• Rolurile sunt interesante. = The roles are interesting.

Breakdown:

• rolurile = the roles
• sunt = are
• interesante = interesting (plural form)

This is a good example of how the neuter noun changes:

• singular: rolul este interesant
• plural: rolurile sunt interesante

It is neutral and completely standard.

• Rolul este interesant. sounds normal and correct.
• Rolul e interesant. is a little more casual and conversational.

Both are common. If you are writing carefully, este is a safe choice. If you are speaking naturally, e is very common.