Learn Hardcore German: Die Bewohner des Hauses, besonders im Erdgeschoss, sagen, die neue Bewohnerin sei freundlich und respektiere die Ruhe. - The residents of the house, especially on the ground floor, say the new female resident is friendly and respects the quiet.

das Haus → genitive singular: des Hauses (article des
- ending -es on the noun)
Bewohner des Hauses literally: inhabitants of the house

You could say Bewohner von dem Haus (usually contracted to vom Haus), and people would understand you, but:

Genitive (des Hauses) sounds more formal and more written.
von + Dativ (von dem Haus) sounds more colloquial / spoken.

In a neutral written sentence like this, Bewohner des Hauses is the most natural choice.

What is the difference between Bewohner and Einwohner?

Both can translate as inhabitant, but they’re used for different kinds of places:

Bewohner
- Typically for buildings or small units:
  - Bewohner des Hauses – the people who live in the house
  - Bewohner der Wohnung – the people who live in the apartment
- Also used more generally for inhabitant of a place.
Einwohner
- Almost always for towns, cities, regions, countries:
  - Die Stadt hat 200.000 Einwohner. – The city has 200,000 inhabitants.
  - Einwohner Deutschlands – inhabitants of Germany.

In this sentence, Bewohner des Hauses is correct because we’re talking about people living in one specific house, not in a town or country.

Why is the phrase die neue Bewohnerin and not die neuen Bewohnerin?

This is about adjective endings.

Noun: die Bewohnerin (feminine, singular, nominative)
Adjective: neu-

With a definite article (die) and a feminine singular nominative noun, the adjective takes -e:

die neue Bewohnerin – the new (female) resident
Pattern: die + Adjective(-e) + feminine noun
e.g. die nette Frau, die alte Lehrerin, die neue Kollegin

Die neuen Bewohnerin would be wrong because -en is not the correct ending in this case. -en appears in other cases (e.g. dative: mit der neuen Bewohnerin), but not in nominative singular feminine with die.

What does Bewohnerin tell us that Bewohner wouldn’t? Why use the feminine form?

German regularly marks biological / social gender on many nouns for people:

Bewohner – male resident, or grammatically generic (could mean “resident(s)” without specifying gender)
Bewohnerin – specifically female resident

By saying die neue Bewohnerin, the sentence makes it clear that:

The new resident is a woman.
We are talking about one specific person (singular).

If we wanted to be neutral / generic, we could say:

der neue Bewohner (traditionally generic masculine, but could be read as male)
die neue Bewohnerin oder der neue Bewohner (explicitly both)
In plural, die neuen Bewohner could refer to a mixed-gender group.

Why does the sentence use sei instead of ist in die neue Bewohnerin sei freundlich?

Sei is Konjunktiv I (subjunctive I), used for reported / indirect speech in written German.

Direct speech:
Die neue Bewohnerin ist freundlich. – The new female resident is friendly.
Reported speech:
Die Bewohner des Hauses sagen, die neue Bewohnerin sei freundlich.
– The residents of the house say (that) the new female resident is friendly.

Using sei shows that we are reporting what someone else says, not directly stating it as the narrator’s own assertion. It:

Does not automatically mean doubt.
Mainly signals: According to them, she is friendly.

In everyday spoken German, many people would simply say:

… sagen, dass die neue Bewohnerin freundlich ist.

But in more formal written German, Konjunktiv I (sei) is very common in news reports, summaries of what others claim, etc.

Why is respektiere also in Konjunktiv, and not respektiert in sei freundlich und respektiere die Ruhe?

Both verbs (sei and respektiere) belong to the same reported statement and share the same subject (die neue Bewohnerin), so they are both put in Konjunktiv I:

sei freundlich – be friendly
respektiere die Ruhe – respect the quiet / peace

If we mixed moods:

sei freundlich und respektiert die Ruhe
this would be grammatically inconsistent: sei (Konjunktiv I) + respektiert (Indicative). It looks like we changed from reported speech back to a plain statement in the middle of the sentence, which is incorrect here.

So we keep both verbs in the same form:

die neue Bewohnerin sei freundlich und respektiere die Ruhe
→ one coherent indirect statement in Konjunktiv I.

Could we rephrase this with dass instead of using sei and respektiere? How would the meaning change?

Yes. Two common alternatives:

Indicative with dass (very common in spoken German):
- Die Bewohner des Hauses, besonders im Erdgeschoss, sagen, dass die neue Bewohnerin freundlich ist und die Ruhe respektiert.
Konjunktiv I with dass (more formal / written):
- … sagen, dass die neue Bewohnerin freundlich sei und die Ruhe respektiere.

Differences:

Without dass + Konjunktiv I (original sentence)
→ stylistically a bit more formal / journalistic, typical of written reports.
Mit dass + Indikativ (ist / respektiert)
→ sounds more natural in everyday spoken language, less formal.
Mit dass + Konjunktiv I
→ very formal, as in official reports or high‑style writing.

The factual meaning is the same: “They say she is friendly and respects the quiet.” The changes are stylistic, not semantic.

Why are there commas around besonders im Erdgeschoss?

Besonders im Erdgeschoss here is a parenthetical adverbial phrase (“especially on the ground floor”). German often separates such inserted information with commas.

Structure:

Die Bewohner des Hauses, besonders im Erdgeschoss, sagen, …
- Main part: Die Bewohner des Hauses sagen, …
- Inserted specification: besonders im Erdgeschoss

The commas tell you that besonders im Erdgeschoss is extra comment / clarification, not essential grammar for the core sentence.

Without the inserted phrase, the sentence still works:
Die Bewohner des Hauses sagen, die neue Bewohnerin sei freundlich und respektiere die Ruhe.

You could also move the phrase:

Besonders die Bewohner im Erdgeschoss sagen, … (slight change in emphasis)
Die Bewohner des Hauses sagen, besonders die im Erdgeschoss, … (again, parenthetical).

In the given version, the commas are required by standard German comma rules for such interrupting modifiers.

Why is it im Erdgeschoss and not something like auf dem Erdgeschoss?

Im is a contraction of in dem (in + dative), and in + Dativ is the normal way to express being in a storey / level of a building:

im Erdgeschoss – on/at the ground floor (literally: in the ground floor)
im ersten Stock – on the first floor
im dritten Stockwerk – on the third floor

Using auf would sound wrong here:

auf dem Erdgeschoss – not idiomatic in standard German for where people live in a building.

So the pattern is:

in
- Dative → im for “on floor X” inside a building.

Why is there a comma before sagen: …, besonders im Erdgeschoss, sagen, die neue Bewohnerin sei …?

There are two comma reasons here:

Closing the inserted phrase
The comma before sagen closes the parenthetical besonders im Erdgeschoss.
- Die Bewohner des Hauses, besonders im Erdgeschoss, sagen, …
Introducing a (that-)clause
After sagen, we have an object clause:
- … sagen, die neue Bewohnerin sei freundlich und respektiere die Ruhe.

In German, subordinate clauses / content clauses like this are always separated by a comma, even when you omit dass.

So the comma before sagen is partly structural (ending the insertion) and partly in preparation for the clause that functions as the object of sagen.