How to create Slices

In the “Catalog” section, I have a Dataset named “Google” with screenshots of websites that feature the Google logo. However, this dataset also contains screenshots that are unrelated to the Google brand, and I need to separate them and create “Slices”. How should I correctly do this, considering that my dataset with Google screenshots is constantly being updated with new images, and there will be more irrelevant pictures that need to be added to the existing “Slices”?
Additionally, on the attached screenshot, I would like to know what these values represent and how to set them. In other words, these “Slices” should filter out screenshots that are unrelated to the Google brand.
If anyone can help me with this?
Thanks!