In last year's Drupal Camp Pune, I gave a session on using Docksal for local development. Slides of the presentation can be found at https://www.slideshare.net/safknw/local-drupal-development-using-docksal.
Block is a very basic building block of any site. Blocks in Drupal 8 are very different from what we are using in d7. In D8 blocks are plugins (like ctool content type plugin) and also an entity. One more major improvement from site builder is that now you can have more than one instance of a block on the same page, all instances can have a different configuration, which was a nightmare in d7. In d7 to achieve this, you have to use either use panels or delta + context modules. Even in this way you can’t have a different configuration for each instance.