If there's one idea that ties all of RemNote together, it's this: everything is a bullet, a small, atomic unit of information. Most bullets are exactly what they sound like, the bullet points you type in the outline editor.
However, bullets aren't always displayed in outline form, and RemNote creates some of them itself. Some things are bullets even though they often won't look like bullet points:
Rows in a table, as well as individual cells in the table
Flashcards are the one exception to this pattern. They aren't bullets themselves; rather, they're associated with and generated from bullets. A flashcard arrow within a bullet causes associated flashcards to be created in the appropriate directions. When you edit the text of or delete a bullet, its associated flashcards are automatically updated.
Each bullet may have up to one parent (a bullet above it in the hierarchy, indented one level closer to the left) and any number of children (bullets below it in the hierarchy, indented one level closer to the right). We can similarly talk about grandparents, grandchildren, and so on, using standard family relations terminology. Collectively, all the bullets higher up the hierarchy than a particular bullet (parents, grandparents, great-grandparents, etc.) are called its ancestors, and any lower down are called its descendants. A top-level bullet is a bullet that has no parent.
You rarely need this vocabulary day to day, but it's handy to have a name for these relationships when you do.
You can quickly jump to or select any bullet using global search (Ctrl+P, or Cmd+P on a Mac) or hierarchical search, or zoom in to it when you can see it in the editor by clicking on its bullet point.