Photos is doing a lot of labelling automatically. It will group the photos according to the dae and the place they have been taken into moment. it helps a lot, if you assign locations to your photos, if you know the places.
Then the moment will show you all photos taken at the same place at the same time. The collections will group related moments, for example photos taken while travelling during a vacation, and a year will show all collections from one year.
Furthermore, Photos will scan the library and classify the photos according to the scenes and objects detected in the photos. After the initial scan you can search for photos with dogs or cats, sunsets, beaches , birthday cakes, christmas trees and many more.
We need only add keywords, titles, descriptions for information, that photos cannot extract automatically, or where the automatic classification is wrong.
I write the categories, that are important to me into the keyword field, and a title for the event depicted in the photo. Put the information into the descriptions, that you will use to search for the photos.and put the information into the titles, that you want to be displayed below the thumbnails.