Take in the View: Exclude the page you're on from a related content list
OSTraining has put together a great use case showing how to use a View's contextual filters to ensure that the page you're on is not included in an attached block displaying related content. The article takes you step-by-step through the process and includes instructive screenshots to help keep you oriented through the process. If you're interested in building Views for your site, click through and take a look.
How to use contextual filters in Drupal 8
Written by Jorge Montoya | OSTraining.com