As my question says, I am wondering what people mean when they say the data follows a normal distribution, does this mean the population follows a normal distribution?
It is hard to guess, where your problem lies, but it seems to me that you have not yet grasped the concept of a sample. The statistical model underlying this concept is as follows:
- A numeric result of a random experiment follows a certain probability distribution.
- The random experiment is repeated independently $n$ times
- The list of results $x_1,\ldots,x_n$ is called a "sample".
The distribution in 1. can be a normal distribution, which is the case to which you refer.