Sunt șapte zile.

In Romanian, sunt can mean both:

• I am
• they are

The subject usually makes it clear.

In Sunt șapte zile, there is no separate word for they, but șapte zile is plural, so sunt is understood as are.

Also, Romanian often uses to be in the same way English uses there is / there are. So:

• Este o problemă. = There is a problem.
• Sunt șapte zile. = There are seven days.

Romanian often does not need a separate word for there in this kind of sentence.

English says:

• There are seven days.

Romanian simply says:

• Sunt șapte zile.

The verb sunt already introduces existence here, so adding a separate there is unnecessary.

Sunt șapte zile is the normal and most natural order for an existential sentence, meaning There are seven days.

Romanian word order is somewhat flexible, but changing it changes the feel:

• Sunt șapte zile. = neutral, natural
• Șapte zile sunt. = unusual on its own; it may sound emphatic, poetic, or incomplete without more context

So for a simple statement of existence or quantity, Sunt șapte zile is the standard choice.

The singular is zi = day.

After șapte (seven), Romanian uses the plural noun:

• o zi = one day
• șapte zile = seven days

So:

• zi = singular
• zile = plural

This is similar to English, where we say one day but seven days.

Because Romanian numbers above one normally take a plural noun.

So:

• un/o zi = one day
• două zile = two days
• șapte zile = seven days

Using șapte zi would be ungrammatical.

A simple learner-friendly pronunciation is:

• Sunt ≈ soont
• șapte ≈ SHAP-te
• zile ≈ ZEE-le

A few helpful notes:

• ș sounds like English sh
• u in sunt is like oo in food
• z in zile is like English z
• Stress usually falls like this: ȘAP-te, ZI-le

So the whole sentence sounds roughly like:

soont SHAP-te ZEE-le

ș is pronounced like English sh.

So:

• șapte sounds like shapte

This letter is very common in Romanian, and it always represents that sh sound.

Yes, Există șapte zile is grammatically possible, but it is not the most natural everyday way to say this idea.

• Sunt șapte zile. = the normal, simple way
• Există șapte zile. = more literal There exist seven days, which sounds more formal or abstract

In ordinary speech, Romanian usually prefers sunt for this kind of sentence.

Because Romanian does not use an article here.

In English, days also has no article in There are seven days. Romanian works similarly:

• Sunt șapte zile. = There are seven days.

If you wanted something more specific, context would show that, but in this basic sentence the noun stays indefinite and plural.

Yes, depending on context, it can also mean something like:

• It is seven days
• They are seven days

But without context, the most natural reading is existential:

• There are seven days

Romanian often allows short sentences like this, and context decides the exact interpretation.