Перепад высот указан на перевале.

Literally, it means difference in heights/elevations.

• перепад = a difference, drop, or change between levels
• высот = of heights/elevations

As a whole, перепад высот is a common Russian expression for elevation difference or height difference.

Because перепад normally takes the genitive to show what kind of difference or change it is.

So Russian is structured like:

• перепад чего?
• высот

The plural is natural because the idea involves comparing more than one elevation point. That is why Russian uses высот rather than a singular form here.

Указан is the short passive participle of указать.

Here it means something like:

• is indicated
• is stated
• is shown

It agrees with перепад, which is masculine singular, so the form is указан.

Compare:

• перепад указан — masculine singular
• высота указана — feminine singular
• значение указано — neuter singular
• данные указаны — plural

In Russian, the present-tense form of to be is usually omitted.

So:

• Перепад высот указан
  literally has no spoken is
• but in English you must translate it as The elevation difference is indicated

If you wanted the past, Russian would include to be:

• Перепад высот был указан = The elevation difference was indicated

Because Russian uses на with many open places, routes, and geographic points, including a mountain pass.

So:

• на перевале = at/on the pass

Using в would suggest being inside something enclosed, which does not fit перевал.

Also, перевале is in the prepositional case, because на takes the prepositional when it means location.

You could, but it changes the feel of the sentence.

• указан = a short passive participle; it focuses on the resulting state: the information is indicated / is marked
• указывается = a present-tense verb; it sounds more like is indicated in a general, habitual, or procedural sense

So in a sign, label, map, or technical description, указан is very natural.

Yes. It is a passive-style sentence: the sentence tells you what is indicated, but not who indicated it.

This kind of wording is very common in:

• signs
• technical descriptions
• maps
• formal written language

English often uses the same kind of passive here: The elevation difference is indicated at the pass.

Yes. Russian word order is flexible.

For example:

• Перепад высот указан на перевале.
• На перевале указан перепад высот.

Both are grammatical. The second version puts more focus on the location first. Russian often changes word order for emphasis or information flow, not because the basic grammar changes.

It can correspond to either one depending on context, but in natural English at the pass is often the better translation.

Russian prepositions do not always match English one-for-one. Here на does not necessarily mean a literal physical on in the English sense. It is just the normal Russian preposition for this location.

The stress is:

перепа́д высо́т указа́н на перева́ле

A rough transliteration with stress would be:

perepád vysót ukazán na perevále