Ela acredita na alma.

Because na is the contraction of em + a:

• em = in / on / at, but after acreditar, it often corresponds to English in
• a = the feminine singular definite article

So:

• em a alma → na alma

With acreditar, Portuguese normally uses em before the thing or idea you believe in:

• acreditar em Deus
• acreditar na sorte
• acreditar no amor

So Ela acredita na alma is the natural way to say She believes in the soul.

Portuguese often uses the definite article where English does not, especially with general ideas and abstract concepts.

So Portuguese commonly says:

• acreditar na alma
• acreditar no amor
• acreditar na vida após a morte

Even though English may say believe in soul in some contexts, the most natural Portuguese here is na alma.

Acredita is the third-person singular present tense form of acreditar.

So it can mean:

• he believes
• she believes
• you believe (formal você)

In this sentence, because we have ela, it means she believes.

Conjugation in the present tense:

• eu acredito = I believe
• você/ele/ela acredita = you/he/she believes
• nós acreditamos = we believe
• vocês/eles/elas acreditam = you/they believe

Yes, very often.

Portuguese is a language that often allows the subject pronoun to be dropped when the meaning is clear from context. So:

• Ela acredita na alma.
• Acredita na alma.

Both are possible.

However, acredita could also refer to he, she, or you (formal), so keeping ela makes it completely clear that the subject is she.

Because alma is a feminine noun in Portuguese.

That is why it takes:

• a alma = the soul
• uma alma = a soul

Even though it ends in -a, which often signals feminine, the important thing is simply that the noun is grammatically feminine and must agree with feminine articles and adjectives.

For example:

• a alma humana
• uma alma pura

Yes. In standard Portuguese, na is the contraction of:

• em + a

Other very common contractions are:

• no = em + o
• nos = em + os
• nas = em + as
• do = de + o
• da = de + a

So here:

• Ela acredita em a alma is not how you would normally say it
• it becomes Ela acredita na alma

Yes. Crer also means to believe, and Ela crê na alma is grammatically correct.

But acreditar is much more common in everyday Brazilian Portuguese. So for most learners, Ela acredita na alma is the more useful and natural sentence to focus on.

Alma is pronounced roughly like AW-ma in Brazilian Portuguese.

A few helpful notes:

• the al at the beginning sounds like aw
• the m is clearly pronounced
• the final a is usually a light unstressed vowel

So a simple approximation for an English speaker is:

• AW-ma

Yes, depending on the structure.

• acreditar em = to believe in
• acreditar
  • statement / idea = to believe

Examples:

• Ela acredita na alma. = She believes in the soul.
• Ela acredita que ele vem. = She believes that he is coming.
• Eu não acredito nisso. = I don’t believe that.

So in your sentence, because it is acredita na alma, the meaning is specifically believes in.

Yes, but Ela acredita na alma is the most neutral and natural order.

Portuguese usually follows the same basic order as English here:

• subject + verb + prepositional phrase

So:

• Ela acredita na alma.

You may also hear other orders in special contexts for emphasis, but for normal learning and everyday use, this standard order is the best one to use.