"Excuse me, do you sell this?" Would be the most common and in my opinion the best English usage... since סליחה eas originally introduced as excuse me in earlier lessons.
I don't think it is. They are all definitions of slikha. Reverso defines it as: Sorry, excuse me, pardon or forgiveness.
"Sorry" on it's own. Or "I'm sorry to bother you" But generally I am sorry ("I'm sorry") it sounds like you did something wrong. That's just me. I hear that I will look around to see what you did wrong!
When you refer to the thing as 'it', it normally means something that you were already talking about. So you could say 'That is a beautiful picture. Are you selling it?'. But if it was the start of a conversation you wouldn't say 'it', perhaps point to it and say 'Excuse me, are you selling this?'
True. My issue is more with Duolingo using phrases as sentences anyway (things that always sound like they're said by a child or non-native English speaker. So on that end, I have to pretend the phrases were plucked out of a book where they do make more sense in context.
Tl;dr: You're saying in English it sounds odd as a stand-alone sentence, but it's a legitimate translation otherwise? Like if you walked in at the tail-end of the conversation, you wouldn't think - that's s weird thing to say!?
Good point about things that sound like a phrase from a non-native English speaker. I just thought that was just the Duolingo Hebrew module - it often seems that the creators are not fully fluent in English.
But about the sentence... I'm not sure which version you are asking about. But assuming it is in the middle of a sentence, 'Excuse me, are you selling it?' sounds fine. Or 'selling this' or even 'selling that'.
And whether it is ok the say 'Sorry' for 'סליחה', might depend on where you are speaking English. In some countries it would sound like an apology, but in other places it would be fine..
Probably not a problem with the DuoLingo App or website. I have installed the Hebrew alphabet on my Android phone, and also on windows. Then you just switch between input languages. Good luck!