അതെന്താണ്? (athethaan?)
This translates literally as "What is that?" and is the most natural and widely understood way to ask this question.
Here are some other variations you can use:
* ഇതെന്താണ്? (ithethaan?) - This is used when the object is closer to you.
* എന്താണത്? (enthaanath?) - This is a more formal way to ask the question.
* എന്താണിത്? (enthaanith?) - This is similar to the previous option but a bit more casual.
Remember that pronunciation is important. The Malayalam language has specific vowel and consonant sounds that might be unfamiliar to you. If you are unsure, it is best to ask a native speaker for help.