'To slip out' means to leave quietly, without people noticing. 'discretely' also means quietly, without a fuss, and/or without drawing attention to yourself. So - basically, he left quietly. ( also - 'here are some dialogues' - you need the plural )

The meaning of disceretly is individually or separately. But when I tried to search it since it's not familiar to me well there's a word which is "discreetly" the meaning of discreetly Is intentionally obtrusive manner, to avoid embarrassment, or to be careful. Which means he slipped out intentionally it means an accident so it not his intention to be slipped out. or maybe he slipped out separately in different direction

Oh thanks for your explanations. The dialogues I wrote are english subtitles on a drama I watched. "discreetly" was right, not discretely. I'll keep them in my mind. thanks!

Gary's explanation (leave quietly) is the one you need, but Pauline has a point: discretely and discreetly have very different meanings. "He slipped out discreetly" is what you meant. By writing "discretely" (=in separate parts), you've given a funny image. Of course, in speech the pronunciation of each word is the same and we'd understand "discreetly".