Formal:
* എന്താണ് ചെയ്യുന്നത്? (enthaanu cheyyunnath?) - This is the most common and direct translation.
* നിങ്ങൾ എന്താണ് ചെയ്യുന്നത്? (ningal enthaanu cheyyunnath?) - This is more formal, using the honorific "ningal" (you) instead of "nee" (you).
Informal:
* എന്താ ചെയ്യുന്നേ? (entha cheyyunnē?) - This is a more casual way of saying it, and is used between friends and family.
* എന്താടാ ചെയ്യുന്നേ? (enthaada cheyyunnē?) - This is a very informal and somewhat slangy way of saying it, and is only used among close friends.
Other options:
* എന്താണ് പണി? (enthaanu paṇi?) - Literally translates to "what is the work?", but is a colloquial way of asking "what are you doing?".
* എന്താ പണിയുണ്ട്? (entha paṇiyundu?) - Similar to the previous option, but more polite.
The best option will depend on the situation and your relationship with the person you are talking to.