They're called acronyms, it's a way to shorten things when phrases are long or complicated. You just say the letters.
ASL is American Sign Language, it's a way of talking for people who can't hear or can't hear well. Clint and one of his daughters has trouble hearing so he is teaching the young kids and anyone else who wants to learn how to talk with their hands so they can communicate easier with more people.
CPR and AED are medical terms. CPR is Cardiopulmonary Resuscitation, and it's a first aid technique that you can perform if someone's heart has stopped. It helps them live long enough for medical attention to have a chance to make things better. AED stands for automated external defibrillator, it's a machine that sends electric pulses through someone's chest to put their heart back in the right rhythm of something has made it go wrong. There are lots of them through the station, but it's better if people know how to use them properly.