Chalk this up to 'things I wish I didn't know', but it's a neo-nazi slogan/concept of 'fourteen words' (something about 'saving the future for white children', yada yada) and 'heil hitler' - 'H' being the 8th letter of the alphabet. '1488-types' are a reference to the type of folks who buy into that horsepuckey.
Right there with you on the wishing I had never heard of it.
I actually started referring to them this way because of an email from Curtis Yarvin to Milo Y. He was giving Milo advice about dealing with 1488 types in a way that doesn't alienate them as an audience.
It's a code nazis use:
14 = the 14 words "we must ensure the existence of our people and a future for white children"
88 = H is the 8th letter, HH = Heil Hitler