The New option allows you to add a slide to your Storyboard directly following the current slide. Clicking on this option will open the Slide Template menu where you will select the type of slide you want to use.
See Slide Types for more information.
The Delete option allows you to remove the current slide from your Storyboard. Clicking this option will result in a confirmation prompt opening. Click Yes to delete or No to cancel.
The Duplicate option allows you to create a copy of the current slide, located directly after. Clicking on this option will copy the slide you were viewing and take you to the duplicate for editing.