As above, a maths/logic thing. But I’ve not used it since doing that course at uni, quite some time ago.
That symbol is not on all keyboards. Pretty sure it is on my home PCs (maybe not chromebook or mac… would need to check), but it certainly is not on this work keyboard. A least it is not labelled on a key but might be available via some weird windoze key combo somewhere.
I’ve always called | a pipe. Have seen the broken vertical also, but again, that one is not on this keyboard.
On this PC, the key that usually has the not symbol, only has the ~ and the backwards ‘ that stuffs up all the formatting on this forum.