Across the top of the screen are 3 import choices: All Photos, New Photos and Destination Folders.

If you click on Destination folders, then Lightroom will show you the folders it is going to use for the destination of the imported images. You have checked the option to Organise by date, so Lightroom shows you all dated folders that will be used if you import all these images. Any dated folders that do not exist yet will be created by Lightroom. If you uncheck certain images, for example all images dated today, then todays dated folder will disappear from the list, because it will not be used.

The numbers to the right indicate the images that can be imported as indicated by the checkboxes. If you expand each of the rows you will see the number of images that corresponds to that number. For example the first expanded row shows the number 6 and each of the 6 images are displayed with checkboxes. If you see images in the window when it is expanded and they are grayed out and uncheckable, it is because those images have already been imported. Hope this helps.