Jeg viser Dem dokumentet på skærmen.

Dem is the formal/polite object form of De (you in a polite or respectful sense).

So in this sentence, Dem means you.

It is capitalized because traditional Danish spelling often capitalizes the formal pronouns De, Dem, Deres to distinguish them from other words and to mark politeness. In modern Danish, this style is less common than it used to be, but you will still see it, especially in formal writing or older-style polite language.

In everyday speech, most Danes would usually say dig instead:

• Jeg viser dig dokumentet på skærmen. = I’m showing you the document on the screen.

Not very common in everyday conversation.

Modern spoken Danish usually uses du/dig even with strangers, customers, teachers, and so on. Using De/Dem can sound:

• very formal
• old-fashioned
• extra respectful
• sometimes distant

So this sentence has a distinctly formal tone.

Viser is the present tense of the verb at vise (to show).

The forms are:

• at vise = to show
• viser = show / am showing / is showing
• viste = showed
• har vist = have shown

Danish present tense is usually made by adding -r to the infinitive:

• vise → viser

So Jeg viser ... means:

• I show ...
• or more naturally in English here, I am showing ...

Because Danish often puts the indirect object directly after the verb, without a preposition.

So:

• Jeg viser Dem dokumentet. literally follows the pattern:
• I show you the document.

This is similar to English I show you the document, where you comes directly after the verb.

If you want, Danish can also use a prepositional construction in some contexts, but with vise, the direct indirect-object pattern is very normal:

• Jeg viser dig billedet. = I’m showing you the picture.

Because dokumentet means the document.

Danish usually adds the definite article to the end of the noun instead of putting a separate word before it.

So:

• et dokument = a document
• dokumentet = the document

This noun is a neuter noun, so its definite ending is -et:

• et dokument
• dokumentet

Skærmen means the screen.

The basic noun is:

• en skærm = a screen

Its definite form is:

• skærmen = the screen

This time the noun is a common gender noun, so the definite ending is -en:

• en skærm
• skærmen

So in the sentence:

• på skærmen = on the screen

Because på is the natural preposition used here for on the screen.

So:

• på skærmen = on the screen

English and Danish prepositions do not always match perfectly, but in this case they do. If something is displayed visually on a monitor or display, på skærmen is the normal expression.

The structure is:

• Jeg = subject
• viser = verb
• Dem = indirect object
• dokumentet = direct object
• på skærmen = prepositional phrase

So the pattern is:

Subject + verb + indirect object + direct object + place/location phrase

That gives:

• Jeg viser Dem dokumentet på skærmen.

This is a very normal Danish sentence structure in a main clause.

That version sounds unnatural.

With pronouns like Dem/dig, Danish strongly prefers placing the indirect object pronoun before the direct object noun:

• Jeg viser Dem dokumentet. ✓
• Jeg viser dig dokumentet. ✓

Putting the noun before the pronoun here is not the normal choice.

It can mean both, depending on context.

Danish does not usually have a separate everyday verb form that exactly matches the English progressive am showing. The present tense often covers both meanings.

So:

• Jeg viser Dem dokumentet på skærmen.

can mean:

• I show you the document on the screen
• I’m showing you the document on the screen

In this context, English would usually translate it as I’m showing you the document on the screen.

The normal informal version would be:

• Jeg viser dig dokumentet på skærmen.

The only change is:

• Dem → dig

Everything else stays the same.

So the contrast is:

• Jeg viser Dem dokumentet på skærmen. = formal
• Jeg viser dig dokumentet på skærmen. = informal/everyday

They are different forms of the same formal pronoun:

• De = subject form (you)
• Dem = object form (you)
• Deres = possessive form (your)

Examples:

• De taler dansk. = You speak Danish.
• Jeg hjælper Dem. = I help you.
• Er dette Deres bog? = Is this your book?

In your sentence, Dem is used because it is the object of viser.

A rough pronunciation guide is:

Yai VEE-ser daim do-go-MEN-ted po SKAIR-men

A few notes:

• jeg is often pronounced something like yai
• viser has stress on the first syllable: VI-ser
• Dem in careful speech sounds roughly like dem/daim
• dokumentet is pronounced more like dogoMENted than a fully clear English-style document
• skærmen has the Danish æ sound, something like the vowel in air, but not exactly

As usual with Danish, real pronunciation is more reduced and smoother than the spelling suggests.