This video goes in to some basics details about both UTM coordinates and Grid Reference and how to use them. It describes how UTM coordinates and Grid References are taken from a map and what is the correct way of passing information about your UTM coordinates or Grid Reference to others, such as a mountain rescue team.
Two other videos are mentioned in this one:
Finding the exact 1cm square at the very centre of Great Britain.
https://youtu.be/KgGOnqPa4e0
How to use a compass to accurately get UTM coordinates and Grid Reference from a map.
https://youtu.be/yfcymnPE304