How to exclude an item from a view if it appears in another view on the same page? I am very new to Drupal and now I am trying to build some small website to try different things out.

I made my website's homepage a Panel, and in it there is a "Promoted News" View, and under this view there is a "Latest News" View.

I want to be able to exclude from "Latest News" any news item that appears in "Promoted News".

Is that possible to do without having to write code? And if not, how can it be achieved?
So you have 2 views: "Promoted News", and "Latest News" View.

To exclude any view results ('items' as you call them) from "Latest News", add a 'filter' in that view with as criteria the opposite (negation) of the 'filter' criteria that are used in your "Promoted News" views.

E.g. if "Promoted News" is implemented with a filter like "published to frontpage", then in "Latest News" the filter o be added should be "NOT promoted to frontpage".

Note: If you're new to Drupal, you might also want to review the set of 30 video tutorials about the Views module to become more familiar with the Views module.