Yellow card is a warning.
Red card is an infraction which accumulates a certain number of points. When you get to a threshold, you then automatically get a ban. If the infraction hasn't expired, you should be able to see how many points there are - IIRC, 3 points gets a 1 day ban, but I may be wrong or it may have changed.
And mods can give you an outright temp ban (of varying length) or a permie ban.
Edit - and there's nothing to stop more than one mod giving you an infraction for the same post, either