this has been explained many times by many people, and views differ from person to person, but...
anglish is essentially a language project that reimagines english without foreign influence from tongues such as latin, greek, and french.
in anglish, speech is grounded in anglo-saxon, without all the long-winded inkhorn words like "antidisestablishmentarianism" or "meteorological".
many folks believe that english-born words should be worthied over borrowed ones, and that they are easier to understand. furthermore, some think that making new words out of english roots to toss out those aforesaid "inkhorn" words is the way to go. (i mean, look at this whole paragraph. barring the inkhorn words in quotations, it was completely anglish!*)
thus, in anglish, there are word such as "witship" to replace "science", and "rimecraft" for "mathematics".
as far as i'm aware, anglish is mostly just an internet thing. you can find anglishers anglishing about over on the subreddit and the discord for that subreddit. also consider reading the the anglish times for world news in anglish.
you can also read all about anglish on anglish.org, and the community wiki
i first found out about anglish in 2023, and i've been part of the community ever since.
although i deem myself a lurker most of the time, i do talk in the anglish reddit sometimes.
eke, ich have mine own wonts for anglish. ich love brooken old an' foryotten words, and speaken mid words of english root over those of northmannish roots ;)
do i sound silly? yes. does picking and choosing archaic words not make sense? also yes. but that's the fun of it :D