We use it if you pass by someone who is working or even by phone . And sometimes people here use it as to say ( peace upon you)
What that means in Arabic and how we can respond?
Speak to male: Yaa’t’eek el a’afyyeh –> يعطيك العافية
Speak to female: Yaa’t’eekii el a’afyyeh –> يعطيكي العافية
Speak to group more than one: yaa’t’eeku el a’afyyeh –> يعطيكو العافية
The respond: to you too!
Answer to male: Allah yia’afeek –> الله يعافيك
Answer to female: Allah yia’afeekii –> الله يعافيكي
Answer to group more than one: Allah yia’afeeku–> الله يعافيكو
Keep in your mind that a good word may be a reason for healing someone or pleasing another!
Speak Arabic As Native 