Translation:It is open until 8 pm.
The 〜て form(progressive tense) is mostly used to indicate an action that is ongoing but It also used to describe an ongoing state resulting from the action. "It is in a state of being open until 8 pm" because it opened and is currently in an open state.
If you go to https://jisho.org/search/%E9%96%8B%E3%81%8F and click on "show inflections" it shows the ways that the pronunciation of 開くchanges under various circumstances.
This comment also sums up the difference between transitive & intransitive: https://forum.duolingo.com/comment/23369832#25611999
EDIT: May've misread the question. If this is about -te form, @sasuke1 explained this in an above comment.
Well, my question was still not answered. What was explained is the need of progressive tense which I perfectly understand. The thing is that the -te form of "akeru" is "akete" and not "aite" so it's still unclear where this came from.
You should be looking for the verb 開く. Remember the English verb 'open' is ergative whereas the Japanese verb '開ける' is not. So in order to express the intransitive sense of the verb 'open' (or in this particular translation, the adjective form of it), Japanese has a different verb, which in this case is 開く and 開いて is its conjunctive form.
You might want to provide a bit more context in your questions; it wasn't apparent to me whether you're asking about verb differences or -te form, etc. Also, did you not check either of the links provided? The second one should've directly answered what you just wrote, with an explanation and examples of 開くvs 開ける. And the first linked to a dictionary entry that provided inflections for the correct verb for this sentence. I edited my original comment though; I think it sounded a bit short-tempered.
Yes, your answers do sound short-tempered. I did check the links but since I still asked the question here, it means I didn't fully grasp those explanations. Besides, discussion section is about particular sentences, not about learning material covered on other websites. Luckily, jamesjiao was kind enough to address my doubts in a clear and polite manner.
I love the pictorials and resemblances of 「門、開き、閉まり」。 So descriptive and straightforward! (･ω･)
It told me "it is open until 8 o'clock pm" is incorrect. Is using "o'clock" not correct in this translation?
This sounds unnatural to me in English - combining "p.m." and "o'clock". I would use one or the other.
I wouldn't say use one or the other. The time of day is required based on the Japanese text that's there, but the o'clock is not. It shouldn't be counted wrong in my opinion, but I do agree that saying "8 o'clock pm" is a more pedantic style than most people would use. Most would say "8 pm" or if they do use o'clock they'd say something like "8 o'clock in the evening".
I thought that way too, but it is "until" 8pm though. Maybe its a good mnemonic to remember "meeting" as you can meet me because im open for business.
even if the て form is used, it is not a command. instead て form with the conjugated いる (here います) forms the progressive tense (not the be opening here but the continuous state of being open, it has been opened and still is)
That sounds wrong to me. "opens" is a verb, so it implies the store is in the act of opening until 8pm, whereas "open" is an adjective, so the store is just in the state of being open until 8pm.