This is a style of writing. It’s like calligraphy, but it uses a pointed instrument, rather than a flat-bladed instrument. You can make fine strokes with the point, or press harder for broader strokes.
The etymology seems murky. A “copper plate” is literally a plate of copper which is etched to form a printing plate. But the relationship between that and the style of writing is vague. Perhaps this style of writing was often used when copper plate printing was popular?
Why I Looked It Up
Honestly, I thought this was just a font – I had seen the name in the font list of lot of applications for years.
Then, I saw a Facebook ad for a Copperplate guidebook is is a workbook-like thing for people to practice their copperplate skills. That was the first inkling that it wasn’t just the name of a font.