Distributions like RHEL and Debian freeze packages, you will have to use old package when the newer is available. I think these distributions is just for highly mission-critical system, they have to run software smoothly, no breakage. Most personal computer don't need that stability.
Can anyone explain more about what a stable distributions mean?
"Stable" doesn't necessarily refer to "reliable," depending on the context. Stable is often used in reference to how often a distro releases new versions of the applications. Using Audacity as an example, in the current release of the distro, they'll release security & bug fixes for version 2, but if you want version 3, you'll have to wait until the next distro release.
Upgrades to a new version of an application can introduce new ways of using the app (i.e. icons in different places, how user-created files are written to disk, etc.), which is disruptive to enterprise op's, which is why Debian & RHEL take this approach.
Hopefully that helps clarify things.