Under Releases are all future releases of Apache OpenOffice listed, including the feature and release planning, developer snapshot builds etc.
<major>.<minor>.<micro> <major>: huge release with visible changes and new features including incompatible API changes if necessary. Translation updates are most often necessary to address the UI visible changes. <minor>: smaller improvements of features that don't need any translation. And of course any kind of bug fixes. <micro>: only selected bug fixes and most often only critical ones. This includes any potential security issues.
See also: https://en.wikipedia.org/wiki/Software_versioning