Below are two different indexes. The first one is a label index. Once a label is selected, a new page will display all the doc pages with that label. It will also allow you to filter it more based on related labels. The second is a page index. It will list all pages by name.
In the Confluence search, you can also manually search with the available operators (AND, OR, NOT). Below are some search examples.
By labels: labelText:windows AND install
By titles: title:windows AND install
By body content: contentBody:windows AND install
By phrase: "windows install" (where 'install' follows 'windows'. Common stop words will be ignored.)
By plain: windows AND install
By group: (windows OR linux) AND install
Then to filter them to this space only use: AND spacekey:FINStack. To filter based on content type, use: AND type:page