Ambos querem ajudar.

Yes. Ambos means both or both of them.

In Ambos querem ajudar, ambos is the subject, so the sentence literally means Both want to help.

A few useful notes:

• ambos = masculine or mixed-gender both
• ambas = feminine both

So if the two people are both female, you would usually say Ambas querem ajudar.

Because ambos refers to two people, so the verb must be in the third-person plural.

The verb is querer = to want.

Present tense:

• eu quero = I want
• você / ele / ela quer = you/he/she wants
• nós queremos = we want
• vocês / eles / elas querem = you/they want

Since ambos means both of them, it matches eles/elas, so you use querem.

This is a very common structure in Portuguese:

• querem = they want
• ajudar = to help

So:

• querem ajudar = want to help

The first verb is conjugated (querem), and the second stays in the infinitive (ajudar).

This works just like English:

• They want to help
• Eles querem ajudar

Because ajudar is in the infinitive form, and infinitives do not change for person in this kind of structure.

Compare:

• Eu quero ajudar = I want to help
• Ela quer ajudar = She wants to help
• Ambos querem ajudar = Both want to help

Only querer changes:

• quero
• quer
• querem

But ajudar stays ajudar.

It is correct, but it sounds a bit more formal or written than some everyday alternatives.

In casual Brazilian Portuguese, people often say:

• os dois querem ajudar = the two of them want to help / both want to help
• as duas querem ajudar = both want to help, for two females

So ambos querem ajudar is perfectly fine, but in conversation many Brazilians would more naturally say os dois querem ajudar.

Yes, but the meaning is slightly less specific.

• Ambos querem ajudar clearly means both of the two
• Eles querem ajudar means they want to help

So eles could refer to two people, three people, or more, depending on context. Ambos specifically emphasizes exactly two.

Because ambos can be used directly as a subject pronoun-like word meaning both.

So:

• Ambos querem ajudar = Both want to help

That is normal and grammatical.

You may also see ambos os... when a noun follows:

• ambos os meninos = both boys
• ambas as meninas = both girls

But in your sentence, there is no noun after ambos, so ambos stands alone.

A simple approximate pronunciation is:

AHM-boos KEH-rem ah-zhoo-DAR

A few pronunciation notes:

• ambos: the am is nasalized slightly
• qu in querem sounds like k
• querem sounds roughly like KEH-rem
• j in ajudar sounds like the s in measure or the zh sound
• final r in Brazilian Portuguese often sounds softer than in English, depending on accent

A rough breakdown:

• Ambos → AHM-bos
• querem → KEH-rem
• ajudar → a-zhoo-DAR

Yes. That is a very natural translation.

Portuguese often does not need to include a separate phrase like of them when ambos already makes the meaning clear.

So these are all good English translations:

• Both want to help
• Both of them want to help

Yes. Ambos can refer to people or things, as long as there are two of them.

Examples:

• Ambos são importantes. = Both are important.
• Ambos funcionam bem. = Both work well.

In your sentence, because of querem ajudar, the subject is naturally understood as people or at least beings capable of wanting to help.

Yes. Both are correct in Brazilian Portuguese.

• Ambos querem ajudar você = Both want to help you
• Ambos querem te ajudar = Both want to help you

In everyday Brazilian Portuguese, te ajudar is very common and natural in speech.

So if you expand the original sentence, you can easily add an object after ajudar.

Yes, sometimes. Portuguese often allows subject omission when the context makes it clear.

So Querem ajudar can mean:

• They want to help
• Both want to help, if the context already makes clear who is being discussed

However, Ambos querem ajudar is more explicit because it clearly states both of them.

If the two people are female, you would usually say:

Ambas querem ajudar.

That is the feminine plural form of ambos.

So:

• ambos = both, masculine or mixed
• ambas = both, feminine only