Sorry. Beta testing (or simply beta) is a lateish test phase of a new software release, before it goes out to the wider wold. Companies like apple release software in a version beta so that people like developers can get their applications (apps) ready for when the new software properly goes live. Also so people can find and report bugs before commercial release.
Generally a beta version is a little bit unstable compared to a full release, so you often find it misbehaves, crashes, or is a bit grumpy - but so far I've found it quite stable personally.