Sorry to say but Nokia has not yet announced the update for this handset to Android v4.4, KitKat. It still has Nokia X Software Platform v1 and will continue to be the same. However, if any update will be there in future you can follow below easy steps to do it:
STEP 1: Go to Settings then About Phone then System updates and then Check Now.
STEP 2: If any updates are available then click on Update
STEP 3: It will take 15-20 minutes for the updates to be installed. You will be asked to restart the phone and during this update you will not be allowed to use your phone.
Some useful details about Nokia XL:
5 inches screen with good viewing angles
5 MP camera with flash and Auto focus
2 MP Front camera
RAM, Battery are decent and have good processing power
Decent user interface