The Peter Rabbit coin is supposed to have a mintage of 1,000 for the silver proof with a household limit of 400. They are making 14 gold proofs with a household limit of 6. They are on sale from 4.15am.
OK, so, this is going to be a simplified version (theoretical physics was never my specialism, I was more an astrophysics kinda gal.
Basically black holes tend to screw with the normal laws of physics. In particular the second law of thermodynamics.
Most of us learned in school that energy can't really be created or destroyed, only transferred. That's the essence of thermodynamics. But it can also be expressed in terms of entropy (entropy is kinda screwy but basically can be thought of as the amount of disorder in the universe) so you can't really create or destroy entropy, only transfer it (crude example, I can neatly line up some rocks, but it takes energy to do that, so the universe hasn't become overall more or less ordered).
Anyway, black holes really screw with this because it's basically a hole. Whatever falls into it is basically "lost" which is bad because it messes with the thermodynamic laws that say that the amount of order in a closed system is constant.
Bekenstein theorised that the only way to explain this contradiction would be if the back holes themselves had some entropy (ie they're not just holes but have some level of order/disorder to them). Hawking's contribution to this was to theorise that black holes actually spit out radiation (Hawking radiation). The formula expresses these quantities mathematically (i.e. the entropy of the black hole is balanced by the radiation it emits).
It's a bit abstract but it's important because it means that black holes aren't actually breaking the laws of thermodynamics. Which is good because frankly physicists have enough other things to clarify around the fringes of the current standard models, so having this bit make sense is really helpful.