https://live.gnome.org/TheBoardProject says:

The Board is a space for quickly placing daily records: photos, video, audio, text, and more. Think of it as a combination of a note-taking app, a photo and video booth, a photo album, a sketching board, and a digital scrapbook.

It would probably be helpful for people new to the concept if that page contained the use cases from the "Adding to the Board" blog post. I know what Cheese is because it is installed on my computer, but if I did not, the link you gave to the project's home page explains that it is a webcam application. I am not sure that the live.gnome.org page is as clear.