Ça dépend du contrat.

In French, ça often means that or it in a very general sense. In Ça dépend du contrat, ça refers to the situation being discussed: that / it depends on the contract.

Using il here would not sound natural. Il usually refers to a specific masculine noun, a male person, or is used in fixed impersonal expressions such as il faut.

So in everyday French:

• Ça dépend. = It depends.
• Ça dépend du contrat. = It depends on the contract.

A more formal version is Cela dépend du contrat.

Dépend is the third-person singular present tense form of the verb dépendre.

So:

• je dépends = I depend
• tu dépends = you depend
• il / elle / ça dépend = he / she / it / that depends
• nous dépendons = we depend
• vous dépendez = you depend
• ils / elles dépendent = they depend

In your sentence, ça is third-person singular, so the verb is dépend.

Because dépendre is followed by de, and contrat is a singular masculine noun that normally takes the definite article le here.

So you start with:

• dépendre de le contrat

But in French, de + le contracts to du:

• de + le = du

So:

• du contrat = of/on the contract

This contraction is mandatory.

Compare:

• de la voiture
• de l’accord
• des conditions

Because dépendre is simply a verb that is constructed with de in French.

So French says:

• dépendre de quelque chose = to depend on something
• dépendre de quelqu’un = to depend on someone

Examples:

• Ça dépend de toi. = It depends on you.
• Tout dépend du prix. = Everything depends on the price.
• Cela dépend des circonstances. = That depends on the circumstances.

Even though English uses on, French uses de after dépendre.

Yes. Ça is the normal, everyday spoken and written form in informal or neutral French. Cela is more formal or careful.

So both are correct:

• Ça dépend du contrat. = everyday, very common
• Cela dépend du contrat. = more formal

In speech, native speakers use ça much more often.

A simple pronunciation guide is:

sa day-pahn dew kohn-tra

A few notes:

• ça sounds like sa
• dépend has a nasal sound at the end, so the final -nd is not fully pronounced like in English
• du sounds like dew, but with a French u sound, which is tighter and more rounded than English oo
• the final t in contrat is usually silent

A rough IPA transcription is:

/sa de.pɑ̃ dy kɔ̃.tʁa/

The verb is dépendre, and the é shows that this vowel is pronounced clearly, like ay in a rough English approximation.

So:

• dé- is pronounced differently from plain de

The accent is part of the correct spelling of the verb and its forms:

• dépendre
• je dépends
• ça dépend

You just have to learn it as part of the verb.

Yes, absolutely. Ça dépend is a very common complete sentence in French, just like It depends in English.

If the context already makes clear what it depends on, you can stop there.

Examples:

• On part demain ?
  — Ça dépend.

• Est-ce que c’est possible ?
  — Ça dépend du contrat.

So du contrat just adds the specific thing the situation depends on.

Yes, in this sentence it normally does. French often uses an article where English may not focus on it as much.

So French says:

• du contrat = on the contract

This refers to the contract in a general contextual sense, or to the relevant contract already understood in the conversation.

Without the article, de contrat would not be correct here.

Yes. After ça dépend de, you can use many things:

• a noun: Ça dépend du contrat.
• a person: Ça dépend de toi.
• a plural noun: Ça dépend des conditions.
• a question word clause: Ça dépend de ce que tu veux. = It depends on what you want.
• an infinitive idea in some contexts: Tout dépend de savoir si... = Everything depends on whether...

So ça dépend de is a very flexible pattern and very useful to learn.