1. Yes, I understand. (with no further elaboration or clarifying questions) 2. It's okay/good/going well (again, with no further elaboration when asking how something is going/set up etc)
First one typically translates to something between "I have a completely unfounded illusion of understanding" and "I have no clue but don't dare to say it"
Second one translates typically to "I have no clue whatsoever"