Tôi tập ở ngoài.

A natural word-by-word breakdown is:

• Tôi = I
• tập = practice, train, or exercise
• ở = at / in / located at
• ngoài = outside

Together, ở ngoài means outside or out there/outside as a location phrase.

So the sentence structure is basically:

• Tôi
  • tập
    • ở ngoài
• I
  • exercise/practice
    • outside

Because ở ngoài is a very common Vietnamese location phrase meaning outside.

• ngoài by itself means outside / outer / out
• ở helps mark it clearly as a location

So ở ngoài works like outside in English.

You can think of it as similar to:

• ở nhà = at home
• ở trường = at school
• ở ngoài = outside

It can mean either, depending on context.

tập is a broad verb that can mean:

• to practice
• to train
• to exercise
• to rehearse

In Tôi tập ở ngoài, many learners will understand it as I exercise outside or I train outside, especially if the overall context is about fitness or sports.

But in another context, it could also mean I practice outside.

Vietnamese often relies on context more than English does.

Not necessarily specifically, but that is a very likely interpretation.

Because tập is general, the sentence could mean:

• I exercise outside
• I train outside
• I practice outside

If you want to make the fitness meaning clearer, Vietnamese speakers often say things like:

• Tôi tập thể dục ở ngoài. = I exercise outside.
• Tôi tập gym. = I work out.
• Tôi tập ngoài trời. = I work out outdoors.

So your sentence is grammatical, but slightly context-dependent.

Vietnamese verbs do not change form for tense the way English verbs do.

So tập stays tập whether the action is:

• present
• past
• future

Time is usually understood from:

• context
• time words
• extra markers

For example:

• Tôi tập ở ngoài. = I exercise outside / I’m exercising outside
• Hôm qua tôi tập ở ngoài. = Yesterday I exercised outside
• Ngày mai tôi sẽ tập ở ngoài. = Tomorrow I will exercise outside

So the basic sentence is tenseless by itself.

Yes, it is grammatical and understandable, but it may sound a little unspecific depending on context.

Native speakers might also say:

• Tôi tập ngoài trời. = I exercise outdoors
• Tôi tập ở ngoài trời. = I exercise outdoors
• Tôi tập bên ngoài. = I exercise outside

Your sentence is fine, but ngoài trời often sounds a bit more natural if you mean outdoors in the open air.

These are similar, but not identical.

• ở ngoài = outside, as a general location
  
  • can mean simply not inside
• bên ngoài = outside / on the outside / externally
  • often emphasizes the contrast with inside
• ngoài trời = outdoors / in the open air
  • especially useful for activities like exercising, eating, or playing sports

Examples:

• Tôi đợi ở ngoài. = I’m waiting outside.
• Tôi đứng bên ngoài. = I’m standing outside.
• Tôi tập ngoài trời. = I exercise outdoors.

So if you mean outdoors in the sense of open air, ngoài trời is often the most precise.

Yes. The most neutral order is:

• Tôi tập ở ngoài.

But Vietnamese can move location phrases for emphasis or topic-setting:

• Ở ngoài, tôi tập.
  = Outside, I exercise.
  This is grammatical, but less neutral and more marked.

Most learners should stick with:

• subject + verb + location

So Tôi tập ở ngoài is the safest standard pattern.

Yes. tập often takes an object to show what you are practicing or exercising.

For example:

• Tôi tập yoga ở ngoài. = I do yoga outside.
• Tôi tập võ ở ngoài. = I practice martial arts outside.
• Tôi tập bài này ở ngoài. = I practice this lesson outside.

Without an object, tập is more general. The listener fills in the meaning from context.

To make it negative, use không before the verb:

• Tôi không tập ở ngoài. = I don’t exercise outside.

To ask a yes/no question, a very common pattern is có ... không:

• Bạn có tập ở ngoài không? = Do you exercise outside?

You can also use the sentence with a question particle in conversation:

• Bạn tập ở ngoài à? = You exercise outside? / Oh, you exercise outside?

So the core sentence is easy to build on.

Not always.

By itself, the sentence can mean different things depending on context:

• I exercise outside as a habit
• I’m exercising outside right now
• I practice outside

If you want to make right now clearer, you can add something like:

• Tôi đang tập ở ngoài. = I’m exercising outside right now.

If you want to make it habitual, context often does the job, or you can add a time phrase:

• Tôi thường tập ở ngoài. = I usually exercise outside.

So the original sentence is neutral and flexible.