It means the coconut milk process is completed!
During the coconut milk function of the Plant Milker, there is a heating process involved.
Once the process is completed, the machine (heating plate) will be at a high temperature for a while.
For safety reasons, the machine is designed to stop working until it cools down and will display "E5" on the screen.
Please allow the machine to cool down for around half an hour. After that, you can add water and run the "Cleaning" function.