Being blocked by someone else means you can't see their posts. I know, a guy I dated who was a narcissist blocked me. I found his account through my second account (that is empty/unused).

Twitter is the place where you can block someone and they can still see your posts/tweets. They don't know they're blocked unless they try to retweet your tweets and can't.

I've blocked a few people. Drama-llamas and such. I only just reactivated in order to talk to one friend.