Operations are the granular, low-level actions that occur while invoking transforms. A single transform could result in many low-level operations being applied to the editor.
Slate's core defines all of the possible operations that can occur on a richtext document. For example:
text:'A new string of text to be inserted.',
text:'A line of text!',
Under the covers Slate converts complex transforms into the low-level operations and applies them to the editor automatically. So you rarely have to think about operations unless you're implementing collaborative editing.
🤖 Slate's editing behaviors being defined as operations is what makes things like collaborative editing possible, because each change is easily define-able, apply-able, compose-able and even undo-able!