What does Natural Selection mean, in a nutshell?

-Natural Selection is simply the Idea that allows Advantageous Phenotypes [So Good Mutations] to be Exploited and Flourished -This is because the Better Mutation is related to the Conditions and Environment, having an Advantage to Live and Reproduce -If they have an Increased Chance of Survival, then the Proportion of the Next Generation, who has the Better Mutation will be Larger -Across a long period of time, the Better Mutation will become simply Normal in all the Population, as its more Adaptive and Efficient