A maioria quer ajudar.

Because maioria is a noun, and in Portuguese it normally takes an article: a maioria = the majority / most.

So:

• a maioria = the majority
• maioria by itself is much less common in a simple sentence like this

In A maioria quer ajudar, a is the feminine singular definite article, because maioria is a feminine singular noun.

Because the grammatical subject is a maioria, which is singular.

Even though the majority refers to many people, Portuguese usually makes the verb agree with the noun maioria, not with the people inside that group.

So:

• A maioria quer ajudar. = standard and natural
• literally: The majority wants to help

This is similar to how collective nouns often work. The idea is plural, but the grammar is singular.

In standard Portuguese, no. The expected form is:

• A maioria quer ajudar.

With a maioria, the safest and most standard choice is a singular verb.

You may sometimes hear variation in speech when a phrase like das pessoas is added, but for learners, the best rule is:

• a maioria → use singular verb

Ajudar is the infinitive form of the verb to help.

After quer (wants), Portuguese normally uses an infinitive:

• quer ajudar = wants to help
• quer comer = wants to eat
• quer sair = wants to leave / go out

So the pattern is:

• quer + infinitive

Because Portuguese does not need a separate word like English to in this structure.

English says:

• wants to help

Portuguese says:

• quer ajudar

The infinitive ajudar already covers the idea of to help.

Yes. Very often Portuguese adds a de phrase:

• A maioria das pessoas quer ajudar. = Most people want to help.
• A maioria dos alunos quer ajudar. = Most of the students want to help.

Here:

• das = de + as
• dos = de + os

So a maioria often appears as:

• a maioria de + plural noun

Yes, a maior parte is another common option.

Compare:

• A maioria quer ajudar.
• A maior parte quer ajudar.

Both can mean the majority / most want to help.
A maioria is often the more direct equivalent of the majority, while a maior parte can feel like most or the greater part.

Both usually take a singular verb as well.

No. In this sentence, ajudar appears without an object, so it simply means help in a general sense.

• A maioria quer ajudar. = Most people want to help.

If you want to say whom they want to help, you can add an object:

• A maioria quer ajudar os amigos. = Most want to help their friends.
• A maioria quer ajudar a família. = Most want to help the family.

In Brazilian Portuguese, ajudar usually takes a direct object without a preposition.

A rough pronunciation is:

• ah my-oh-REE-ah keh-r ah-zhoo-DAR

A few notes:

• maioria has the stress on ri: mai-o-RI-a
• quer in Brazil sounds roughly like kehr
• ajudar has the stress on the last syllable: a-zhu-DAR

The j in ajudar sounds like the s in measure or the zh sound.

No. It can be used for people, things, ideas, votes, objects, and more.

Examples:

• A maioria quer ajudar. = most people want to help
• A maioria dos livros chegou. = most of the books arrived
• A maioria dos votos foi válida. = most of the votes were valid

So a maioria is a general expression meaning the majority / most of some group.

Yes, but the meaning changes.

• A maioria quer ajudar. = The majority wants to help
• Quer ajudar? = Do you want to help? / Does he/she want to help? depending on context
• Quer ajudar. by itself usually means He/She wants to help or can sound incomplete without context

So in the full sentence, a maioria is important because it tells you who wants to help.