Registers in a CPU

Question

https://en.wikipedia.org/wiki/Processor_register So from the information in this link there are limited Floating point and General Purpose registers in a cpu. My question is how are these registers used. By that I mean let's say I defined some variables in python but I think It's stored in RAM or HDD so does cpu only use those registers when operating on the data fetched from RAM and if so in order to overload cpu's capacity what kind of an algorithm should be followed by such a program ?