The navigation block has 2 modes you can toggle between using the "manually picked nav" switch.

The default list mode allows to select a node from the content tree and the navigation block will automatically list all child nodes.

The manual select mode allows you to select the internal pages using the "manually selected items" property

Both modes can be displayed as blocks or a list, use the "Nav Display" property to choose.

Hidden toggle: shows/hides block

Background colour: Adds a background colour to the whole block

Navigation title/Anchor: creates an anchor link that you can use to link to from a navigation object e.g. url#anchorlink

CSSClass: you'll not need to use this

Remove gap: Remove the top padding from the block so it sits tight to the preceding block.