Blocking is when you can't get words out of you. I block frequently enough, but I know what I want to say. No noise, no air, etc. gets out so most people wouldn't even know unless I was in the middle of a sentence or a speech where there would be no reason for the sentence to just end. My stuttering improved over time, but it took a long time. Every stutterer is different though. When I was in kindergarten, I struggled to even form a sentence, let alone have it be understood by others. I had a friend who would translate it to people, which was sweet. I would see a speech therapist. They will help you figure out speaking techniques and the cause or reason for your stutter or speech impediment.