What is the user 'mobile' for on iPad?

I just sshed to a jailbroken iPad(Pro 3, iOS 14.2), and found other than root and daemon, there's an existing user mobile, which seems to come with the system. I was wondering 1. what the user is for? 2. if I do not change the password, can others ssh to my device with this account? 3. if I do change the password, can it mess with the normal system operation?