Emotional Regulation is quite simply the ability to adult. We develop our self regulation skills as we grow and these include the ability to keep calm when we want to get angry, monitor what we do and say so we mostly say appropriate things.
There are two classifications of emotional regulation skills; adaptive (the good ones) and maladaptive (the bad ones). Teens with ASD often develop too many of the maladaptive skills; the adaptive ones are still present but they are not the skills drawn on automatically.
As with anything in life – sometimes adaptive and maladaptive strategies overlap. For instance there are times when internalizing emotions are good such as if someone has just died – it is natural to become quiet and introspective – however when this goes on too long and you are always internalizing emotions, this can be a bad thing thus a maladaptive strategy.