What does it mean that separate observations from interpretations?

What you saw and what you concluded from it are distinct and must not be fused.

Example: Your coworker didn't respond to your Slack message for four hours. That's the observation. 'She's ignoring me because she's upset about the code review' is the interpretation. Write both down — separately. The observation is stable. The interpretation is a hypothesis you can test, revise, or discard.

Try this: Pick one situation from the last 24 hours that triggered a strong reaction. Write two separate entries: (1) the raw observation — only what a camera would record, and (2) the interpretation — what you concluded it meant. Look at the gap between them. That gap is where most of your errors live.