Die Außeneinheit steht hinter dem Haus.

Because hinter is a two-way preposition in German. That means it can take either:

• dative for a fixed location
• accusative for movement toward a place

In this sentence, the outdoor unit is located behind the house, so German uses dative:

• hinter dem Haus = behind the house

If there were movement to that position, you would use accusative:

• Die Außeneinheit wird hinter das Haus gestellt. = The outdoor unit is placed behind the house.

German often uses position verbs where English would simply use is.

Here, stehen literally means to stand, but it is also commonly used for things that are upright or installed in a standing position. So:

• Die Außeneinheit steht hinter dem Haus.

sounds natural in German for a unit or device that is physically standing there.

English often just says is behind the house, but German prefers to be a bit more specific with verbs like:

• stehen = stand
• liegen = lie
• hängen = hang

Because Außeneinheit is a feminine noun.

The main part of the compound is Einheit, and Einheit is feminine, so the whole compound noun is feminine too:

• die Einheit
• die Außeneinheit

In this sentence, the noun is the subject, so it is in the nominative singular, and the correct article is die.

It is a compound noun, which is very common in German.

It is made up of:

• außen = outside / exterior
• Einheit = unit

Together, Außeneinheit means outdoor unit or external unit.

A useful rule: in German compound nouns, the last part usually determines the gender and basic meaning. Here the last part is Einheit, so the whole word is feminine.

Because all nouns are capitalized in German.

So in this sentence:

• Außeneinheit is a noun
• Haus is a noun

Both must begin with a capital letter.

This is one of the most noticeable differences from English.

Yes. That is completely correct.

German main clauses follow the verb-second rule, which means the conjugated verb must stay in the second position. So both of these are correct:

• Die Außeneinheit steht hinter dem Haus.
• Hinter dem Haus steht die Außeneinheit.

The difference is mainly emphasis:

• Die Außeneinheit ... puts the focus first on the unit
• Hinter dem Haus ... puts the location first

Here, hinter means behind.

So hinter dem Haus means behind the house or at the back of the house.

It usually describes position relative to the house. It does not necessarily mean the unit is touching the house; it just tells you where it is located.

The subject is die Außeneinheit, which is third person singular.

The verb is stehen, and in the present tense the third person singular form is steht.

A few forms of stehen are:

• ich stehe
• du stehst
• er/sie/es steht
• wir stehen
• ihr steht
• sie/Sie stehen

So die Außeneinheit steht is the correct agreement.

A rough pronunciation guide is:

• Außen: the äu sounds a bit like oy
• ß is pronounced like ss
• Einheit begins with ein, which sounds like English ine in line, but shorter

So Außeneinheit sounds roughly like:

• OW-sen-eye-nite

That is only approximate, but it helps.

Not necessarily.

Außeneinheit is a general word for an outdoor/external unit. Depending on context, it could refer to:

• an air-conditioning unit
• a heat pump unit
• another external technical device

So the exact object depends on the situation, but the grammar of the sentence stays the same.