I personally think of it as 'có' being added because it's saying that the table 'has' this quality. The table isn't pretty when pretty is a noun. Pretty is an adjective so it 'has' this quality rather than is a noun. Hope that makes sense and please correct me if I'm wrong! :)
According to the mouseover on the word, it can mean "nice" when used for objects.
May be a glitch, but I cannot hear the audio of the speaker, even though I can hear the rest of the app.
I have this throughout the app, someone said they dont have all the tranlations so it is wierd why they would have the audio button but i dunno
Should khong have isn't added and the translation be Isn't the table nice? Thats how my wife described it and i knew it was not, so to me it would make more sense this way to make that connection.