Der Wartungsvertrag nennt die Wartungspauschale.

Yes. Der Wartungsvertrag is the subject of the sentence.

• der = the masculine singular nominative article
• Wartungsvertrag = maintenance contract

So Der Wartungsvertrag means the maintenance contract, and it is the thing doing the action of nennt.

Because the two nouns have different genders and different roles in the sentence.

• Wartungsvertrag is masculine, so in the nominative singular it takes der
• Wartungspauschale is feminine, and here it is the direct object, so in the accusative singular it takes die

That gives us:

• der Wartungsvertrag = nominative subject
• die Wartungspauschale = accusative object

For feminine nouns, die is used in both nominative and accusative singular, so the role is understood from the sentence structure and the verb.

nennt is the 3rd person singular present tense form of the verb nennen.

The conjugation is:

• ich nenne
• du nennst
• er/sie/es nennt
• wir nennen
• ihr nennt
• sie/Sie nennen

Since the subject is Der Wartungsvertrag (a singular noun), the verb must be nennt.

Here, nennen means something like:

• to name
• to mention
• to state
• sometimes to specify

In a business or legal sentence like this one, nennt often sounds more like states or specifies than everyday calls.

So this is not necessarily about giving something a nickname. It is more likely saying that the contract mentions or states the maintenance fee.

Because this is a normal main clause, and German main clauses usually follow the verb-second rule.

The structure is:

• Der Wartungsvertrag = first element
• nennt = finite verb in second position
• die Wartungspauschale = rest of the sentence

That is standard German word order.

Yes. Both are classic German compound nouns.

Wartungsvertrag

• Wartung = maintenance
• Vertrag = contract

So: maintenance contract

Wartungspauschale

• Wartung = maintenance
• Pauschale = flat fee / lump sum / fixed charge

So: maintenance flat fee or fixed maintenance charge

German often builds long nouns this way instead of using separate words like English does.

There is actually no extra -s- in Wartungsvertrag.

It is simply:

• Wartung
  • Vertrag → Wartungsvertrag

The g of Wartung is followed directly by v of Vertrag.

In some German compounds, you do get a linking element such as -s-, called a Fugenlaut, but not here.

Example with a linking -s-:

• Arbeitsvertrag = work contract / employment contract

So this sentence does not show that pattern.

The object is die Wartungspauschale.

You can tell because:

1. Der Wartungsvertrag is nominative, so it is the subject.
2. nennen normally takes a direct object.
3. The sentence pattern is the common German order: subject + verb + object.

So the contract is doing the naming/mentioning, and the maintenance fee is the thing being named/mentioned.

Yes, but it would sound more marked or stylistically different.

For example:

• Die Wartungspauschale nennt der Wartungsvertrag.

This is grammatically possible, but it puts stronger focus on die Wartungspauschale. In many contexts it sounds less natural than the original sentence.

The original version is the most neutral and straightforward:

• Der Wartungsvertrag nennt die Wartungspauschale.

Because all German nouns are capitalized.

So in this sentence:

• Wartungsvertrag is capitalized
• Wartungspauschale is capitalized

This is a basic spelling rule in German and applies whether the noun is simple or part of a compound.

Usually not, because the meaning would change.

• nennen = to name, mention, state, call something
• heißen = to be called, to have the name

So:

• Der Wartungsvertrag nennt die Wartungspauschale.
  = The contract mentions/states the maintenance fee.

But Die Wartungspauschale heißt ... would mean:

• The maintenance fee is called ...

That is a different structure and a different idea.

Because in this sentence the case is mainly shown by the articles, not by noun endings.

Compare:

• der Wartungsvertrag
• die Wartungspauschale

The nouns Wartungsvertrag and Wartungspauschale stay the same. What changes is the article, depending on gender, number, and case.

This is very common in German, especially with singular nouns in simple sentence patterns.