A Question About Stats

So recently I got a ring, known as Wastelands, which gives a lot of poison. 137/3s to be exact. And this got me wondering.

How do you calculate these stats actually, like Mana Regen, Life steal etc? I can clearly tell when something gives a lot of said stats, according to how big the numbers are, but I want a bit more accurate information. So could you, the person reading this post, help me?

Thank you for your time, have a nice day, evening or whatever time it is where you live

 

It means that after a hit, the entity will receive 137 damage over 3 seconds.