The End Step marks the end of a branch in a robot.
This step is a useful marker to have at the end of a branch, since clicking on it enables all steps in the branch to execute. Without it another step would have to be inserted at the end in order to be able to execute the last step of the branch.
The End Step is not associated with any action and is comparable to an action step with a Do Nothing action when it comes to its execution. An End Step cannot be deleted, but several branches may share the same End Step.
Note: the End Step does not stop execution of a robot. For this you should use an action step with a Stop action.