I am trying to figure out what these web page means for the version. I know that the epoch is the number previous the double dot. But I can't figure out what this all means ?
I found this here
As you noted, the epoch is the number in front of a colon, specifically used in Debian pacakges.
If the scheme of upstream package version changes or if there was an error with an upload, the epoch of a package can be increased to remain a consistent ordering of packages with different versions, which is e.g. important at any system update.
The page you found just lists the security reports with a wrong/missing epochs. This happens when the current epoch of a package was not used when entering the versions of the package in which a security problem was solved.
These are database inconsistencies, which are requested to be solved. The effect is that the affected security problems could be wrongly marked as solved in too early package versions.