If you're "perfectly fine" with something, it means that you don't have any problems with it:
If you want to smoke in your own home, that's perfectly fine. But other people shouldn't have to breathe in your smoke while they're trying to enjoy a meal at a restaurant.
"Perfectly ___" is usually used to disagree with what someone else said:
A: Stop getting upset.
B: What are you talking about? I'm perfectly calm.
Or you can use it to express a contrast between two ideas:
You state an action that you're perfectly fine with by saying "I'm perfectly fine ___ing":
I'm perfectly fine just staying home and chilling out today.