Die Endreinigung beginnt heute oder morgen.

German very often combines nouns into a single compound noun.
So Endreinigung = End + Reinigung, meaning something like final cleaning or end-of-stay cleaning.

This is completely normal in German. English often uses separate words, but German prefers one combined word.

Examples:

• Hausaufgabe = house + task = homework
• Badezimmer = bath + room = bathroom
• Endreinigung = final + cleaning

Die is the definite article, meaning the.

In this sentence, die Endreinigung is the subject:

• Die Endreinigung = the final cleaning

The noun Reinigung is feminine, and the compound noun keeps the gender of its final part. Since Reinigung is feminine, Endreinigung is also feminine.

So:

• die Reinigung
• die Endreinigung

Yes. Beginnt is the third-person singular present tense of beginnen = to begin.

Here is the pattern:

• ich beginne
• du beginnst
• er/sie/es beginnt

Since die Endreinigung is singular, the verb is beginnt.

German often uses the present tense to talk about the future when the time is clear from context.

Because the sentence includes heute oder morgen (today or tomorrow), it is already obvious that the event is in the near future. So German does not need a special future form here.

That is very common:

• Ich komme morgen. = I’m coming tomorrow.
• Der Kurs beginnt nächste Woche. = The course starts next week.

You could use wird beginnen, but it would usually sound less natural here.

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

In this sentence:

1. Die Endreinigung
2. beginnt
3. heute oder morgen

So the structure is:

• subject
• verb
• time information

This is one of the most important German word-order rules.

German often puts time expressions after the verb, especially in simple statements like this one.

So:

• Die Endreinigung beginnt heute oder morgen.

This sounds natural and neutral.

You can move parts around for emphasis, but then the verb still stays in second position:

• Heute beginnt die Endreinigung.
• Morgen beginnt die Endreinigung.

In your sentence, heute oder morgen simply gives the time information in a straightforward way.

Yes, that is possible.

Both mean roughly the same thing:

• Die Endreinigung beginnt heute oder morgen.
• Die Endreinigung fängt heute oder morgen an.

But there is a style difference:

• beginnen is a bit more formal or neutral
• anfangen is a bit more conversational

So beginnt fits especially well in written notices, schedules, or formal communication.

It is in the nominative case because it is the subject of the sentence.

You can ask:

• What begins today or tomorrow?
• The final cleaning begins today or tomorrow.

That makes die Endreinigung the subject, so nominative is used.

Because all nouns are capitalized in German.

So in this sentence:

• Endreinigung is a noun, so it gets a capital letter
• heute and morgen here are not nouns, so they are lowercase

This is a standard German spelling rule.

Here it means tomorrow.

German morgen can mean:

• tomorrow as an adverb
• morning in some contexts, usually as part of am Morgen or as the noun der Morgen

In your sentence:

• heute oder morgen = today or tomorrow

So it is definitely tomorrow here.

Yes. Heute oder morgen shows uncertainty between two possible times: today or tomorrow.

So the sentence suggests that the final cleaning will start on one of those two days, but the exact day is not fixed or not being stated precisely.

Yes. Endreinigung is especially common in contexts like:

• holiday apartments
• rental properties
• moving out
• cleaning services
• construction or renovation cleanup

It usually means the final cleaning done at the end of a stay, rental period, or job. So it is a practical, real-world word you will often see in notices or contracts.