“Wheat meat” has been around for hundreds of years, but the name “seitan” (which you say “say-tan”) is much newer. Seitan is made from wheat, but it is not like flour or bread. Seitan looks and feels a lot like meat when cooked, which is why vegetarians and vegans often use it as a meat substitute. It is also called wheat protein, wheat gluten, and gluten.
To make Eitan, wheat flour and water are mixed and kneaded until strands of gluten protein form in a sticky dough.