Mọi người phải theo luật.

Yes. Mọi người means everyone / everybody / all people.

• mọi = every, all
• người = person, people

So mọi người is a very common way to say everyone in everyday Vietnamese.

One thing to note: depending on context, mọi người can also mean everyone here / you all / folks, not just humanity in general. In this sentence, it means everyone in a general sense.

Vietnamese does not use articles the same way English does.

So:

• luật can mean law, the law, or sometimes rules/laws, depending on context.
• mọi người already clearly means everyone, so no article is needed.

Vietnamese often leaves this kind of definiteness to context rather than marking it with words like the or a.

Phải here means must, have to, or be required to.

In this sentence:

• mọi người = everyone
• phải = must / have to
• theo luật = follow the law / act according to the law

So phải expresses obligation.

Be careful: phải can mean different things in other contexts, such as correct/right in some uses, but here it is clearly the modal verb must.

Because Vietnamese often puts modal verbs like phải before the main verb.

The pattern is:

subject + modal verb + main verb + object/complement

So here:

• Mọi người = subject
• phải = modal verb
• theo = main verb
• luật = object/complement

This is similar to English:

• Everyone must follow the law.

So the structure is actually quite parallel to English.

Here, theo means to follow or to act according to.

So theo luật means:

• follow the law
• act according to the law
• abide by the law

This is not the same as physically following a person, although theo can also mean that in other contexts.

Examples:

• theo mẹ = follow mom
• theo luật = follow the law / according to the law

So the meaning depends on what comes after theo.

It is understandable and acceptable, but many learners will also hear more explicit versions such as:

• tuân theo luật
• theo đúng luật
• tuân thủ pháp luật

These can sound a bit more formal or more precise.

Roughly:

• theo luật = follow the law / according to the law
• tuân theo luật = obey the law
• tuân thủ pháp luật = comply with the law

So Mọi người phải theo luật is fine, but in very formal contexts Vietnamese might use a fuller expression.

It can depend on context.

Luật most often means law in the legal sense. But in some contexts, especially less formal speech, people may loosely understand it as rules.

If you want to be more specific:

• luật = law
• pháp luật = the legal system / the law in a formal sense
• quy định = regulations
• nội quy = internal rules, house rules, school/company rules

So in this sentence, the most likely meaning is the law.

Vietnamese does have verbs meaning obey, but it does not have to use them.

For example:

• tuân theo = obey, follow
• tuân thủ = comply with
• chấp hành = comply with, carry out, obey (often official/formal)

But Vietnamese also often expresses the idea with a simpler verb like theo when the meaning is clear.

So:

• Mọi người phải theo luật = Everyone must follow the law.
• Mọi người phải tuân theo luật = Everyone must obey the law.

The second version is a bit more explicit.

Yes, very often in conversation.

For example, someone speaking to a group may say:

• Mọi người ăn cơm chưa? = Have you all eaten yet?

In that case, mọi người means something like everyone here or you all, not literally every person in the world.

In your sentence, though, it is best understood as everyone in general.

A very literal breakdown is:

• Mọi người = every person / everyone
• phải = must
• theo = follow
• luật = law

So, word-for-word:

Everyone must follow law

Natural English adds the: Everyone must follow the law.

Yes. Ai cũng phải theo luật is another natural way to say Everyone must follow the law.

• ai = who / anyone
• cũng = also, all, equally in this pattern

Together, ai cũng means everyone or anyone/everyone alike, depending on context.

So:

• Mọi người phải theo luật
• Ai cũng phải theo luật

Both are natural, though they feel slightly different in style.

A rough pronunciation guide is:

• Mọi ≈ moy (with a heavy falling tone)
• người ≈ something like ngwee-uh or ngwuh-ee, depending on accent
• phải ≈ fye or fy-eye (with a dipping/glottalized tone in Northern speech)
• theo ≈ tay-oh but smoother, closer to theo
• luật ≈ loo-uht with a short clipped ending

Important points:

• Vietnamese tones matter.
• người and luật are tricky for English speakers because of the vowel combinations and final sounds.
• Exact pronunciation differs somewhat between Northern and Southern Vietnamese.

If you are learning pronunciation, it is best to listen to native audio rather than relying only on English approximations.

It is mostly neutral and straightforward.

• Not especially casual
• Not especially formal
• Easy to understand

For a more formal or official tone, Vietnamese might prefer:

• Mọi người phải tuân thủ pháp luật.
• Mọi người phải chấp hành pháp luật.

For ordinary speech, Mọi người phải theo luật is simple and clear.