Hi.
The Panda does not have a hydraulic power steering system. It it electrically assisted, so no fluid to top up.
Is this just a maintenance enquiry or do you have a problem?
OK. That's fairly well covered on the forum.
Usual reasons in order of probability & cost are:
Poor earth connections
Weak battery
Failing torque sensors in power steering unit.
Search on here for suggestions on how to proceed.