Learn Hardcore Japanese: kono heya ha sizukade, akarui desu.

It marks the topic of the sentence: この部屋 (this room). So the sentence is “As for this room, ….” Although written は, the topic particle is pronounced wa. Pronunciation: kono heya wa shizuka de, akarui desu.

What is the で after 静か? Is it the place/means particle で?

Here で is the connective (te-form) of the copula used with a na-adjective: 静かだ → 静かで. It links descriptions and means “and.” It is not the location/means particle.

Why isn’t it 静かなで?

な is only used when a na-adjective directly modifies a noun (e.g., 静かな部屋). When you connect a na-adjective to another predicate with the te-form, you use 静かで, not 静かなで.

Is it correct to put です after an i-adjective like 明るい?

Yes. 明るいです is standard polite speech. In casual speech you can drop です (明るい). Do not use だ with i‑adjectives.

Do I need the comma or the spaces?

Spaces are not used in normal Japanese writing and were added for learners. The comma 、 is optional. Natural writing: この部屋は静かで、明るいです or この部屋は静かで明るいです.

Can I say 静かで明るい部屋です instead? Is there any difference?

この部屋は静かで明るいです: “This room is quiet and bright.” (predicate description)
この部屋は静かで明るい部屋です: “This room is a quiet, bright room.” (modifies the noun; slightly redundant but acceptable) Both are correct; the first is leaner.

Can I reverse the order and say 明るくて、静かです? Any nuance change?

Yes: この部屋は明るくて、静かです is fine. Use くて for i-adjectives. The final adjective tends to receive slight emphasis, so you can choose the order to highlight what you want to stress.

What’s the rule for で vs くて when linking?

na-adjectives and nouns: use で (e.g., 静かで、便利です; 和室で、広いです)
i-adjectives: use くて (e.g., 明るくて、広いです)

Is で here the same で as in “at/in/by”?

No. Same spelling, different function. Here it’s the connective form of the copula (linking adjectives). The location/means で attaches to nouns (e.g., 部屋で勉強する “study in the room”).

Could I use が instead of は: この部屋が静かで、明るいです?

You can, but the nuance changes:

は marks the topic (“as for this room…”), neutral description.
が marks the subject and often adds focus/contrast (“It’s this room that is quiet and bright”), useful when answering “Which room…?”

Can I drop です for a casual sentence?

Yes.

Polite: この部屋は静かで、明るいです。
Casual: この部屋は静かで、明るい。 Even more casual/topic-drop: この部屋、静かで明るい。

Why not use だ to connect: 静かだ、明るいです?

だ ends a clause; it doesn’t link it. To connect, use the te-form: 静かで、明るいです. If you want two separate sentences, that’s fine: 静かだ。明るいです。

Does 明るい mean “bright” or “cheerful”?

Both, depending on the noun. With 部屋, it means “bright/well‑lit.” With a person (明るい人), it means “cheerful/outgoing.”

How do I add more adjectives?

Link all but the last:

この部屋は静かで、明るくて、広いです。 na-adj → で, i-adj → くて, last adjective carries the final です.

How do I make it negative or past?

Negative: この部屋は静かじゃなくて、明るくないです。
Past: put tense on the last predicate; it scopes over the linked set:
- この部屋は静かで、明るかったです。 (“was quiet and bright”)