It has two components that bring the bright red color. One of them is Gochujang- a fermented chilli paste which is not at all spicy but has a strong umami flavour. The second one is gochugaru- red chilli flakes which are pretty spicy. If you’re trying to make Kimchi you can totally skip it.

If you get to try Kimchi at a restaurant it’s probably not too spicy and mellow.