Bar None British slang
Nothing/ no one else is better.
She is the most beautiful girl I have ever met in my life, bar none.
This is the most interesting film that I have ever watched, bar none.
To become better
We should be careful in doing everything instead of doing something risky.
Used to tell someone not to stress about something
A: I'll help you prepare the dinner.
B: I am really into cooking myself, so don't worry your pretty little head about it.