Lazy loading images means loading images on websites asynchronously. This can be done by showing images only when they appear in the browser’s viewport. If users don’t scroll all the way down, images placed at the bottom of the page won’t be loaded. The purpose of this is to make users feel that your website loads quickly.
On Twitter, Google’s John Mueller said that not all methods for lazy loading images work with Google:
There are various ways to lazy-load images, it's certainly worth thinking about how the markup could work for image search indexing (some work fine, others don't). We're looking into making some clearer recommendations too.— John ☆.o(≧▽≦)o.☆ (@JohnMu) 28. February 2018
Unfortunately, John Mueller did not get into detail. Among many other things, the website audit tool in SEOprofiler checks the speed of your web pages. You can create your free SEOprofiler account here: