Não há espaço na mochila.

Here, há means there is / there are in the sense of existence.

So Não há espaço na mochila literally works like:

• não = not / no
• há = there is / there are
• espaço = space / room
• na mochila = in the backpack

A very literal translation would be There is not space in the backpack, but in natural English you would usually say There’s no room in the backpack or There isn’t any space in the backpack.

Because Portuguese often uses haver to express existence.

In English, we say:

• There is a problem
• There is space
• There isn’t room

In Portuguese, one formal/common way to express that idea is with haver:

• Há um problema
• Há espaço
• Não há espaço

So há is not the same as is. It is part of an existential structure, like English there is.

Both can be used in Brazilian Portuguese, but they are different in style.

• Não há espaço na mochila sounds more neutral, careful, or slightly more formal.
• Não tem espaço na mochila is very common in everyday spoken Brazilian Portuguese.

So:

• Não há espaço na mochila = more standard/written
• Não tem espaço na mochila = very natural in conversation

A learner should recognize both. If you want a safer, more standard form for writing, não há is excellent.

In this use, no. When haver means there is / there are, it is impersonal, so it stays in the singular form há.

Examples:

• Há um livro na mesa. = There is a book on the table.
• Há dois livros na mesa. = There are two books on the table.

Even with a plural noun, Portuguese still uses há, not a plural verb form.

So you do not say hão espaço or anything like that.

Because Portuguese often leaves out the article when talking about something in a general or indefinite way.

Compare:

• Não há espaço na mochila. = There is no space in the backpack.
• Não há o espaço necessário na mochila. = There isn’t the necessary space in the backpack.

In your sentence, espaço is being used as a general idea, not as a specific, already-identified space. That is why no article is needed.

This is similar to English, where we also usually say no space, not no the space.

Na is a contraction of:

• em = in
• a = the

So:

• em + a = na

That means na mochila literally equals in the backpack.

Other common contractions like this are:

• no = em + o = in the
• nos = em + os = in the
• nas = em + as = in the

Because Portuguese usually uses an article with many common nouns when referring to a specific thing.

So:

• na mochila = in the backpack

If you said em mochila, it would sound incomplete or unnatural in normal Portuguese.

The article is built into na, so the sentence is already saying in the backpack, not just in backpack.

Yes. Não existe espaço na mochila is grammatically correct and understandable.

However, there are some nuance differences:

• Não há espaço na mochila = very natural, standard, compact
• Não existe espaço na mochila = also correct, but can sound a little more emphatic or formal depending on context
• Não tem espaço na mochila = very common in spoken Brazilian Portuguese

In many everyday situations, não há espaço and não tem espaço are the most likely choices.

Yes, in this kind of sentence espaço often corresponds to English space or room.

So these are all natural translations:

• There is no space in the backpack.
• There isn’t any space in the backpack.
• There’s no room in the backpack.

English often prefers room when talking about available capacity, even though the Portuguese word is espaço.

A rough pronunciation guide for Brazilian Portuguese is:

nowng ah es-PAH-soo nah mo-SHEE-lya

A few notes:

• não has a nasal sound, which is hard to represent in English
• há sounds like ah
• espaço has stress on pa
• mochila has stress on chi

If you want to sound more natural, the sentence usually flows together smoothly, something like:

não há espaço na mochila

with the stress mainly on há, pa, and chi.

In this specific sentence, it most naturally refers to physical space inside the backpack.

So the idea is that the backpack is full or too full.

In other contexts, espaço can also mean space in a broader sense, including metaphorical uses, but with na mochila, the meaning is clearly physical capacity.