La durada és al contracte.

Al is the contraction of a + el.

So:

• a el contracte → al contracte

In this sentence, al contracte is usually understood in English as in the contract. Catalan often uses a where English would use in.

És is the 3rd person singular of ser: is.

A very common learner question is this one, especially if they know Spanish. Catalan uses ser much more often than Spanish for simple location or where something is found.

So La durada és al contracte is a normal structure for saying that the information is found there.

Because durada is a feminine singular noun, so it takes la:

• la durada

It also shows that we are talking about a specific duration, not the concept of duration in general.

Durada is a noun meaning duration or length.

It is related to the verb durar (to last).

So:

• durar = to last
• durada = duration

The accent is important because it distinguishes és from es.

• és = is
• es = a pronoun used in reflexive/pronominal constructions

So the accent is not optional here.

Contracte is masculine:

• el contracte

That is why the sentence has al contracte and not a la contracte.

Yes, it is grammatical and understandable.

That said, in formal or document-related language, Catalan speakers might also say things like:

• La durada consta al contracte.
• La durada figura al contracte.

Those can sound a bit more natural when you mean that the information is written in the document.

A rough guide for an English speaker is:

luh doo-RAH-duh ehs ahl kun-TRAK-tuh

A few useful points:

• durada is stressed on ra
• és is stressed and clearly pronounced
• contracte is stressed on trac

Exact pronunciation will vary by dialect, but the stress pattern stays the same.