Die Software stellt verblasste Farben wieder her.

Because the verb is wiederherstellen, which is a separable verb.

In a normal main clause in the present tense, the conjugated part goes to position 2, and the separable prefix goes to the end:

• wiederherstellen → stellt ... her

So:

• Die Software stellt verblasste Farben wieder her.

This is very common in German:

• Ich rufe dich an. = I call you up.
• Er steht früh auf. = He gets up early.

In an infinitive or participle, the verb is usually written together again:

• Die Software kann verblasste Farben wiederherstellen.
• Die Software hat verblasste Farben wiederhergestellt.

Here, wiederherstellen means to restore.

It is built from:

• wieder = again
• herstellen = to produce, make, create, manufacture

But as a single verb, wiederherstellen usually means:

• to restore
• to recover
• to bring back to an earlier state

So in this sentence, the idea is that the software restores colors that have faded.

Because Software is a feminine noun in German:

• die Software

Even though it comes from English, German assigns it grammatical gender, and the standard gender is feminine.

So you get:

• die Software = the software
• eine Software = a software program / a piece of software

And in the sentence, Die Software is the subject.

Because Farben is the plural of die Farbe:

• die Farbe = the color
• die Farben = the colors

The sentence is talking about faded colors in general, not just one color.

So:

• verblasste Farben = faded colors

If it were singular, it would be something like:

• Die Software stellt die verblasste Farbe wieder her. = The software restores the faded color.

Because verblasste Farben is in the accusative plural without an article.

The noun phrase is just:

• verblasste Farben

There is no die or diese in front of it, so the adjective takes the strong ending. For accusative plural, that ending is -e:

• verblasste Farben

Compare:

• Die Software stellt verblasste Farben wieder her.
• Die Software stellt die verblassten Farben wieder her.

In the second sentence, die is present, so the adjective ending changes to -en.

verblasste means faded.

It comes from the verb verblassen = to fade.

So:

• verblasste Farben = faded colors

This is basically a past-participle-like adjective describing the colors as having lost strength or brightness.

A learner-friendly way to think of it is:

• verblassen = to become faded
• verblasst / verblasste = faded

It is near the end because it is the separable prefix of wiederherstellen.

In a main clause:

• the conjugated verb goes in second position: stellt
• the separable prefix goes to the end: her

Notice that wieder is not being moved separately as an adverb here. It is part of the full verb wiederherstellen.

So the structure is:

• Die Software = subject
• stellt = conjugated verb
• verblasste Farben = object
• wieder her = the separated verb parts together at the end area

You can think of wieder her here as belonging together semantically: restore.

It is in the accusative case, because it is the direct object of the verb.

Ask the question:

• What does the software restore?

Answer:

• verblasste Farben

So the software is the thing doing the action, and the faded colors are the thing receiving the action.

That gives us:

• Die Software = nominative subject
• verblasste Farben = accusative object

Because German main clauses normally follow the V2 rule: the finite verb comes in the second position.

Here the first position is taken by the subject:

• Die Software | stellt | verblasste Farben wieder her.

So stellt must come second.

German does not mean “second word” exactly, but second sentence element. For example, you could also say:

• Verblasste Farben stellt die Software wieder her.

That is less neutral, but still grammatical. The finite verb stellt is still in second position.

Yes. stellt is the present tense form of stellen used as part of wiederherstellen.

So the sentence means something like:

• The software restores faded colors.
• The software is restoring faded colors.

German present tense often covers both simple present and present progressive meanings that English separates.

Usually, wiederherstellen is the more natural choice here.

restaurieren does exist and means to restore, but it is often used for things like:

• paintings
• buildings
• furniture
• works of art

For digital image correction, wiederherstellen sounds more general and natural.

So for software restoring faded colors in an image, Die Software stellt verblasste Farben wieder her is a very good choice.