Android - App Update Manifest Version Code and Name

Android - App Update Manifest Version Code and Name

my Android Manifest File :
my existing Version Code = 1
also
my existing Version Number = 1
I want to update my App and I know that have to change my Version Number
e.g. to 1.1 but what does the Version Code mean?
Should it stay at 1?
Or do i have to change it also? Maybe be to 2? oder anything else?
Thx for ur help!