מחזיר האור על השלדה המקורית.

By itself, it reads most naturally as a phrase or caption, not a full sentence.

A very natural way to parse it is:

• מחזיר האור = the reflector / the light reflector
• על השלדה המקורית = on the original frame/chassis

So the whole thing is more like the reflector on the original frame than a full English-style sentence.

If Hebrew wanted a full sentence, it would usually add something like נמצא or another clear predicate, for example:

• מחזיר האור נמצא על השלדה המקורית.
  The reflector is on the original frame.

Probably not in this phrase.

On its own, מחזיר can be:

• a present-tense verb form: returns / is returning
• or a participle used like a noun, something like returner or reflector

Here, because of the structure מחזיר האור, it is most naturally understood as a noun-like participle: reflector.

So this is not most naturally returns the light, but rather the light-reflector / the reflector.

That is one of the biggest clues that מחזיר is not functioning as a normal verb here.

If the meaning were returns the light, Hebrew would normally say:

• מחזיר את האור

The word את marks a definite direct object. Since the phrase is מחזיר האור without את, האור is not being treated as the direct object of a verb. Instead, the two words are being read together as a unit, roughly the light-reflector.

Because this is most naturally a construct chain type of phrase.

In Hebrew construct phrases, the definite article often appears only on the second word, while the whole phrase is still definite.

A classic example is:

• בית הספר = the school
  literally: house of the book

In the same way:

• מחזיר האור can function as the reflector / the light-reflector

So even though מחזיר itself does not have ה־, the whole expression can still be definite.

Here על most naturally means on.

So:

• על השלדה המקורית = on the original frame/chassis

Depending on context, על can also mean over, onto, or even about, but in this sentence the physical-location meaning on is the most likely one.

Because in Hebrew, adjectives normally come after the noun they describe.

So:

• שלדה מקורית = an original frame
• השלדה המקורית = the original frame

This is the normal Hebrew order:

• noun first
• adjective second

That is different from English, where we usually put the adjective first.

Because Hebrew adjectives must match the noun in definiteness.

So if the noun is definite:

• השלדה = the frame

then the adjective must also be definite:

• המקורית = the original

That gives:

• השלדה המקורית = the original frame

Compare:

• שלדה מקורית = an original frame
• השלדה המקורית = the original frame

You usually cannot make only one of them definite.

It is feminine singular.

You can tell because:

• שלדה is a feminine singular noun
• מקורית is the feminine singular form of the adjective מקורי

So the adjective agrees with the noun:

• מקורי = masculine singular
• מקורית = feminine singular
• מקוריים = masculine plural
• מקוריות = feminine plural

Hebrew would usually remove the definite articles:

• מחזיר אור על שלדה מקורית

That would be more like:

• a light reflector on an original frame

Compare the article patterns:

• מחזיר אור = a light reflector
• מחזיר האור = the reflector / the light-reflector
• על שלדה מקורית = on an original frame
• על השלדה המקורית = on the original frame

So the ה־ prefixes are doing a lot of important work in this sentence.