ELI5: Explain Like I'm 5

Population proportion

When we talk about population proportion, we are basically talking about how many people out of the whole group have a certain trait or characteristic.
For example, imagine you have a group of 100 children and you want to know how many of them have brown hair. If you count and find out that 20 of them have brown hair, then the population proportion of children with brown hair is 20% (because 20 out of 100 is 0.20, which is the same as 20%).
Basically, we are looking at a small part of a bigger group and trying to figure out how common or uncommon a certain trait or characteristic is in that group.