Comment by antonvs

If you're a native English speaker you've probably seen it, even if you didn't know what it meant.

A common context in which it's used is in the idiom "herald a new era" - here's a search: https://www.google.com/search?q="heralds+a+new+era" which shows that it's pretty common.

It's also used in the names of many newspapers around the world: https://en.wikipedia.org/wiki/Herald_(newspaper)

There's also the Christmas carol, "Hark! The Herald Angels Sing": https://en.wikipedia.org/wiki/Hark!_The_Herald_Angels_Sing

But I suppose if you don't already know the word "herald" you might just put that down to weird religious language.