Todos precisam respeitar a lei.

Todos is plural, so it means everyone / all people.

• todo = singular, usually every or whole
  • todo dia = every day
  • o dia todo = the whole day
• todos = plural
  • todos precisam = everyone needs / all people need

In this sentence, todos is being used by itself as a pronoun, so the noun is understood: todos (as pessoas).

Because precisam agrees with todos, which is plural.

Basic present-tense forms of precisar:

• eu preciso
• você / ele / ela precisa
• nós precisamos
• vocês / eles / elas precisam

Since todos is grammatically plural, the verb must also be plural:

• Todos precisam...

If the subject were singular, you would use precisa:

• Todo cidadão precisa respeitar a lei.

In this sentence, todos is best understood as everyone or all people.

It can have both ideas depending on context:

• todos os alunos = all the students
• todos by itself = everyone / all of them

So in Todos precisam respeitar a lei, the noun is omitted, and todos works like everyone.

Because after a conjugated verb like precisam, Portuguese commonly uses an infinitive to express the second action.

Structure:

• precisar + infinitive
• precisam respeitar = need to respect

This is very similar to English need to respect, except Portuguese does not use a separate word like to before the infinitive here.

Other examples:

• Eu preciso estudar. = I need to study.
• Eles precisam sair. = They need to leave.

In Brazilian Portuguese, when precisar is followed by a verb, the normal pattern is:

• precisar + infinitive

So:

• precisam respeitar = need to respect

But when precisar is followed by a noun, you usually use de:

• precisam de ajuda = they need help
• preciso de dinheiro = I need money

So the contrast is:

• precisar respeitar
• precisar de algo

Because Portuguese normally uses the definite article here.

• a lei = the law

In this sentence, a lei refers to the law in a general institutional sense, not to one specific law that was just mentioned. Portuguese often uses the article in cases like this.

So:

• respeitar a lei = respect the law

Leaving out the article would sound unnatural here.

Yes, but only if you are talking about an all-female group.

• todos = masculine plural, also used for mixed groups or when gender is unspecified
• todas = feminine plural only

So:

• Todos precisam respeitar a lei. = everyone / all people need to respect the law
• Todas precisam respeitar a lei. = all of them need to respect the law, and the group is female

Yes, it is natural and correct. It sounds neutral and standard.

A very common everyday alternative in Brazilian Portuguese is:

• Todo mundo precisa respeitar a lei.

That also means everyone needs to respect the law.

There is also:

• Todos têm que respeitar a lei.

This is also very common and often feels a bit more conversational than precisam.

So the original sentence is perfectly good, especially in formal or general statements.

Yes, but Todos precisam respeitar a lei is the most neutral and natural order.

This is the standard pattern:

• subject + verb + infinitive + object

Other orders are possible for emphasis, but they are less neutral:

• A lei todos precisam respeitar.
  This is more emphatic or stylistically marked.

For learners, the safest choice is the original order:

• Todos precisam respeitar a lei.

A simple approximate pronunciation is:

• TOH-dos preh-SEE-zãw hes-pey-TAR a LEY

A few helpful notes:

• todos: the o in the first syllable is open in many accents
• precisam: the final -am is nasal in Brazilian Portuguese
• respeitar: the ei sounds like ay in say
• lei sounds like lay

If you say it slowly in chunks, it helps:

• Todos
• precisam respeitar
• a lei

Usually yes. Todos means everyone in the group being talked about, and that normally includes the speaker if the speaker is part of that group.

For example, if someone says:

• Todos precisamos respeitar a lei

that clearly includes the speaker, because the verb precisamos is we need.

But even with Todos precisam respeitar a lei, the general idea is still broad and inclusive: everybody is expected to respect the law.