'Publication citations' refers to the number of times that a publication has been cited by other publications in the Dimensions database. (Publications here includes more than just research articles, but also books/chapters, monographs, preprints, and conference proceedings).
As a standard measure of the impact a paper has, citations are the most commonly used indicator of the acceptance/importance of published work within the research community. This is despite the fact that the number of times cited does not include any indication of the nature of a citation (favourable, or merely observational), or whether it has been cited in a primary research or review paper. The number of times cited is also closely related to the length of time since the paper was originally published, as even papers which represent a breakthrough in their field will have a low citation count if they have been published recently.
Aggregated indicators based on citations - available in the Analytical Views
'Citations per publication' is an aggregated citation-based indicator; it is calculated by dividing the total number of citations by the total number of publications.
'Cited/Not Cited' is the percentage of publications that have been cited one or more times vs. publications which haven't been cited yet.