Is there ... an explanation which explains what it all means?
It's an attempted improvement on the policy survey at http://meta.wikimedia.org/wiki/EU_policy/Survey
"A survey about the importance of various policy issues ... given the highest priority by our community."
If you are having trouble working the preference ballot at http://demochoice.org/dcballot.php?poll=wmfcsdraft then please try the demonstration, instructions, and background material at http://demochoice.org/
The ranked-preference ballot makes respondents consider choices pairwise, which has an accuracy advantage over approval (yes or no to each) or Likert scale (e.g. 1 "strongly agree" to 5 "strongly disagree") responses when respondents are not familiar with all the options. Approval on an issues survey can have problems with relatively disproportionate numbers of responses with only a few options or all or almost all options selected, and the Likert scale gets fewer responses on issues less familiar to respondents than ranking.
Best regards, James