Tớ muốn nước ép không đường.

Tớ means I / me, but it is informal and friendly. It is commonly used:

• with friends
• with classmates
• with people around your age when the relationship is casual

It is not the neutral pronoun for all situations. In other contexts, you might use:

• tôi = more neutral or formal
• mình = friendly, soft, common in casual speech
• em = used when you are younger than the listener, or in certain polite service situations

So Tớ muốn nước ép không đường sounds like something you might say casually, not in a very formal setting.

Yes, muốn literally means want. In many cases, Tớ muốn... is a normal way to say I want... or I’d like....

However, when ordering food or drinks, Vietnamese often sounds more natural with structures like:

• Cho tớ một ly nước ép không đường.
• Cho mình nước ép không đường nhé.
• Mình muốn một ly nước ép không đường.

So your sentence is understandable and correct, but in a café, many speakers would choose a slightly smoother ordering phrase.

Nước ép means juice.

Literally:

• nước = water / liquid / drink
• ép = press / squeeze

So nước ép is basically pressed liquid, which became the normal expression for fruit juice.

Examples:

• nước ép cam = orange juice
• nước ép dứa = pineapple juice
• nước ép táo = apple juice

In Vietnamese, descriptive elements often come after the noun.

So:

• nước ép không đường = juice without sugar / unsweetened juice

This is different from English, where we usually put modifiers before the noun:

• sugar-free juice
• unsweetened juice

In Vietnamese, it is very natural to say:

• cà phê không đường = coffee without sugar
• trà không đá = tea with no ice
• bánh mì không ớt = bread/sandwich with no chili

So the order is: main item + thing you do not want

In everyday ordering language, không đường usually means no sugar added.

That is important because fruit juice naturally contains sugar from the fruit itself. So in a café, if you say:

• nước ép không đường

people will normally understand:

• Please do not add extra sugar.

If you want to be extra clear, you can say:

• nước ép không thêm đường = juice with no added sugar

But in practice, không đường is very common and usually understood correctly.

Not always, but very often it sounds more complete in real-life ordering.

Your sentence:

• Tớ muốn nước ép không đường.

means:

• I want unsweetened juice.

This is fine if the type or amount is already understood. But when ordering, Vietnamese often includes a container or serving word such as:

• một ly = one glass
• một cốc = one cup/glass
• một chai = one bottle

So a fuller version would be:

• Tớ muốn một ly nước ép không đường.

That sounds more like a real order.

Yes, it is natural enough and clearly understandable. But there are even more typical ways to order.

Common natural versions include:

• Cho tớ một ly nước ép không đường.
• Cho mình một ly nước ép không đường.
• Mình muốn một ly nước ép không đường.

Why?

• cho in ordering often works like please get me / I’ll have
• including một ly makes the order feel more complete
• mình can sound softer than tớ in some situations

So your sentence is correct, but it is slightly more like stating a desire than placing a polished order.

Yes, and in Vietnamese this matters a lot, because pronouns depend on relationship, age, and situation.

For example:

• Tôi muốn nước ép không đường.
  Neutral, but can sound a bit stiff or direct in casual service situations.
• Mình muốn nước ép không đường.
  Friendly, soft, very common in casual speech.
• Em muốn nước ép không đường.
  Used if you are younger than the person you are speaking to, or if that social role fits.
• Con muốn nước ép không đường.
  A child speaking to a parent.

So the sentence structure stays the same, but the pronoun changes depending on who is speaking and to whom.

Vietnamese often does not need an exact equivalent of English to have in this kind of sentence.

English might say:

• I want to have some unsweetened juice
• I’d like an unsweetened juice

Vietnamese simply says:

• Tớ muốn nước ép không đường.

That is enough. Vietnamese is often more direct in structure:

• subject + want + thing

So there is no missing word. The sentence is complete as it is.

A few words here are especially hard for English speakers:

• tớ
  The ớ vowel is not like a normal English o. It is a central rounded vowel, and the tone rises.
• muốn
  Watch both the vowel cluster and the tone. It is not pronounced like English moon.
• nước
  This is a very common difficult word. The ươ sound does not exist in English, and the final c is unreleased.
• đường
  Again, ươ is tricky. Also, đ is a normal voiced d sound, unlike plain d in Vietnamese orthography.

A rough learner-friendly guide:

• tớ ≈ tuh with a rounded vowel and rising tone
• muốn ≈ moo-uhn with the correct Vietnamese vowel quality and tone
• nước ≈ noo-uhk, but much shorter and tighter
• đường ≈ doo-uhng, with the proper Vietnamese vowel

These rough spellings are only approximations. If you want, I can also break the whole sentence down syllable by syllable with tone notes.