Simple explanation of some things. It is not meant for long explanations, but just a short form. People can use a search engine if they want more info.
Akademy is the yearly conference for KDE Contributors and other interested persons.
Baloo is the new file indexer
BoF is workshop/discussion session about a topic. https://en.wikipedia.org/wiki/Birds_of_a_feather_(computing)
KDE eV is the non-profit organization supporting KDE and keeps KDE's assets.
Kirigami is a toolkit (QtQuick components) for making mobile and other applications.
Nepomuk is the old indexing service, now mostly retired.
Okular is a document reader (PDF's and other files) released as part of KDE Applications
Randa is a remote place in Switzerland where Mario Fux close to every year arranges a large week long hacking sprint.