This post is a jargon-free & simple description of these measures:
Remember the last time you tried to click a link & the link changed it’s position. And, this caused your click to land you on a different page? This metric addresses such experiences.
Remember when you tap a button, link or text-box as the page is loading and nothing seems to happen forever? This metric addresses such experiences.
The time when the largest visible content element on screen is fully displayed.
To understand the above metrics in greater detail, check this Google web.dev article.
Your feedback, thoughts & opinion on the above are welcome.