وضعية الجسم جيدة على الجهاز البيضاوي.

Because in Arabic, the verb to be is usually omitted in the present tense.

So:

• وضعية الجسم جيدة = The body’s posture is good
• literally: Body posture good

This is called a nominal sentence in Arabic. The sentence is still complete and natural without a present-tense is.

If you wanted a past tense, then Arabic would use a verb such as كانت:

• كانت وضعية الجسم جيدة = The body posture was good

وضعية means something like position, posture, or body positioning, depending on context.

In this sentence, it most naturally means posture or body position.

A useful distinction:

• وضع often means placement, putting, or situation
• وضعية is often more like positioning, stance, or posture

So وضعية الجسم is a natural way to say body posture or the position of the body.

What you are seeing is the normal way Arabic is usually written: without short vowel endings.

With full case endings, it would be:

• وضعيةُ الجسمِ جيدةٌ على الجهازِ البيضاويِّ

Here:

• وضعيةُ has -u because it is the subject
• الجسمِ has -i because it is the second word of an iḍāfa construction
• جيدةٌ has -un because it is the predicate
• الجهازِ البيضاويِّ comes after على, so both are in the genitive

In everyday writing, those endings are usually not written.

Because وضعية الجسم is an iḍāfa construction, often called a possessive or genitive construction.

It literally works like:

• وضعية الجسم = posture of the body = the body’s posture

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun can be definite, and that makes the whole phrase definite

So even though وضعية has no الـ, the full phrase وضعية الجسم is definite because الجسم is definite.

Because it agrees with وضعية, which is a feminine singular noun.

Arabic adjectives agree with the noun they describe in:

• gender
• number
• definiteness

Here the relevant noun is وضعية, not الجسم.

So:

• وضعية = feminine singular
• جيدة = feminine singular

Even though الجسم is masculine, the adjective is not describing الجسم directly. It is describing the whole subject phrase وضعية الجسم.

Because البيضاوي describes الجهاز, and جهاز is masculine.

So the adjective must match الجهاز:

• الجهاز البيضاوي = the elliptical machine/device

If the noun were feminine, then the adjective would also be feminine. For example:

• الآلة البيضاوية = the elliptical/oval machine

So in your sentence:

• الجهاز = masculine
• البيضاوي = masculine

Literally, it means something like:

• the oval device
• or the elliptical machine

In real usage, it refers to the elliptical trainer / elliptical machine used for exercise.

So this is one of those cases where the literal meaning and the natural English meaning are slightly different:

• literal: the elliptical device
• natural English: the elliptical machine

على usually means on or upon.

So:

• على الجهاز البيضاوي = on the elliptical machine

This matches English pretty well. You are physically exercising on that machine, so على is natural.

In other contexts, Arabic prepositions may not match English exactly, but here على is a straightforward choice.

It is an adjective in form, but in this sentence it functions as the predicate of a nominal sentence.

Structure:

• وضعية الجسم = the subject
• جيدة = the predicate
• على الجهاز البيضاوي = a prepositional phrase adding context

So the sentence means:

• The body posture is good on the elliptical machine

If you wanted good to be part of the noun phrase itself, as in the good body posture, you would say:

• وضعية الجسم الجيدة

That is different from:

• وضعية الجسم جيدة

The first is a noun phrase; the second is a full sentence.

وضعية is pronounced roughly waḍʿiyya in pause.

A very important detail: the ة (tāʾ marbūṭa) is often pronounced like -a / -ah when you stop on the word, but it is pronounced like t when followed grammatically by another word in a construction like iḍāfa.

So:

• by itself: وضعية ≈ waḍʿiyyah
• in وضعية الجسم: the ة is effectively pronounced as t, so it is closer to waḍʿiyyat al-jism

This is very common in Arabic.

Yes. That is a valid, more literal translation.

Possible translations include:

• The body posture is good on the elliptical machine.
• The body’s position is good on the elliptical machine.
• Body posture is good on the elliptical machine.

Which one sounds best depends on context:

• in fitness or exercise language, posture is often the most natural
• in a more neutral or technical context, position may also work

So the Arabic allows a small range of natural English translations.

It would be:

• وَضْعِيَّةُ الجِسْمِ جَيِّدَةٌ عَلَى الجِهَازِ البَيْضاوِيِّ

This shows the grammar clearly:

• وضعيةُ = subject, nominative
• الجسمِ = second term of iḍāfa, genitive
• جيدةٌ = predicate, nominative
• على = preposition
• الجهازِ = genitive after على
• البيضاويِّ = adjective matching الجهازِ in definiteness, gender, number, and case

Most normal Arabic writing leaves these endings off, but knowing them helps you understand the structure.