Here’s what that means:
The state value of sensor.target_temp_michael must decrease from a value higher than 26 to a value lower than 26 and then remain lower for at least 1 minute and then it will trigger the automation.
If the current state value of sensor.target_temp_michael is already lower than 26, this automation will not be triggered. The value must first rise above 26 (this resets the Numeric State Trigger) and then fall below 26 (and remain below 26 for over a minute) before it will trigger again.
So if the sensor’s value is currently below 26, the automation won’t be triggered. You will have to wait until it rises above 26 then falls below it again.