‘Nodes’ and ‘Knots’ mean the same thing as used here, and that is they refer to the outline points which are drawn and selectable.
Some things you can do with nodes on an outline:
•Select a node by clicking on it.
•Edit nodes by dragging them around.
•Add nodes by double-clicking where you want one to appear, and you can double-click a node to remove it.
•Drag around a set of nodes, in which case you will select all the ones in your “lasso”.
•Right-click while nodes are selected and change properties and do other things with the outline.