Learn Hardcore Korean: i gageneun yeongeopsigani gireoseo pyeonhae. - This shop’s business hours are long, so it’s convenient.

-아서/어서 feels natural/casual and often states a factual cause-and-effect.
-(으)니까 highlights the speaker’s reasoning/justification and is preferred when the main clause is a command/suggestion.
-(으)기 때문에 is more formal/neutral and explicit: “because.”
All three can work here with nuance changes: 길어서, 길으니까, 길기 때문에.

Why do we have both 는 and 이: 이 가게는 … 영업시간이 …?

이 가게는: 는 sets the topic (“as for this store”).
영업시간이: 이 marks the subject of the embedded clause (영업시간 is what is “long”).
So it’s “As for this store, (its) business hours are long, so (it’s) convenient.” Topic outside; subject inside.

Can I write 영업시간 with a space (영업 시간)?

Both appear in real life, but the standard and most common form is the compound noun without a space: 영업시간 (“business hours”). You’ll see 영업 시간 on signs for readability or style, but 영업시간 is safer.

Could I say 이 가게가 영업시간이 길어서 편해 instead of 이 가게는 …? What changes?

Yes.

이 가게는 …: topical, gives a general comment about this store.
이 가게가 …: subject-focused, often contrasting with other stores (this one, specifically, is convenient). Both are grammatical; pick based on emphasis.

What politeness level is 편해, and how do I make it more polite/formal?

편해 is casual/informal (반말).

Polite: 편해요
Formal: 편합니다
Past: 편했어 / 편했어요 / 편했습니다
Future: 편할 거야 / 편할 거예요 / 편할 것입니다

Does 편하다 mean “comfortable” or “convenient” here? How is it different from 편리하다 and 편안하다?

편하다 covers both “comfortable” and “convenient,” and is the go-to in everyday speech. Here it means “convenient.”
편리하다 = “convenient” in a more formal/technical tone (signs, manuals).
편안하다 = “comfortable/at ease” (physical/mental comfort), not “convenient.”
Examples: 이 앱은 편해/편리해. (convenient) vs 이 소파는 편안해. (comfortable).

Why use … 길어서 편해 instead of … 길고 편해?

길고 편해 = “(the hours) are long and (the store) is convenient” (just listing two facts).
길어서 편해 = “(it’s) convenient because (the hours) are long” (explicit cause). The original sentence wants causation.

Can I drop -서 and say 영업시간이 길어 편해?

Yes, in casual speech/writing -어/-아 can replace -어서/-아서: 길어 편해. It sounds a bit snappier/informal. For careful or formal contexts, keep -어서/-아서.

How do 길어서, 길으니까, and 길기 때문에 differ in nuance?

길어서: neutral, conversational cause-and-effect.
길으니까: speaker’s reasoning/justification; fits well before advice/commands.
길기 때문에: explicit, slightly more formal/objective.
All are fine here: choose based on tone and context.

Who/what is the subject of 편해? Is it “the store,” “I,” or “it”?

Grammatically, the topic 이 가게는 is what’s being described, so “This store is convenient.” Semantically, Korean often omits an implicit subject like “using/going to it,” so it’s understood as “It’s convenient (to use/go to this store).” This ellipsis is natural.

Is 영업시간이 길다 natural, or should I say “open late” instead?

영업시간이 길다 is natural and common. Alternatives you’ll also hear:

늦게까지 열어서/영업해서 편해. (They open until late.)
24시간 영업이라서 편해. (They’re open 24 hours.)
Pick the one that fits what you want to highlight.

Any pronunciation tips for this sentence?

영업시간이 is typically [영업시간이], and in fast speech the ㅅ in 시간 may sound tense: [영업씨간이].
길어서 is [기러서] (the ㄹ links smoothly).
편해 is [펴내].
Don’t overthink it; keep the rhythm smooth: yeong-eop-si-gan-i gi-reo-seo pyeon-hae.

How do I change the tense/aspect?

Past: 이 가게는 영업시간이 길어서 편했어/편했어요.
Future: … 길어서 편할 거야/편할 거예요.
Ongoing relevance: keep the present: 편해/편해요.

Can I use -어서 when giving a suggestion or command?

Prefer -(으)니까 for suggestions/commands. For example:

Better: 영업시간이 길으니까 나중에 가자. (Since hours are long, let’s go later.)
Using -어서 here feels less natural with proposals/imperatives.