One of the things that does cause people problems with Twitter is the use of hashtags. I don't think that it's because they're difficult - it's because they can't believe that they're so easy to use! A hashtag is a controlled vocabulary keyword preceded by the hashtag (#) symbol. Except that it's not very well controlled, since people can just make them up for themselves to emphasis something - a little like emboldening or underlining, while others use them in a far more controlled manner in order to gather together tweets from an unknown group of people who are all tweeting about the same thing.
There are tools out there which help you make sense of them, and one such has Hashtagify.me which has a number of helpful features. You can simply put in the name of a hashtag, and it will find related tags, key influencers (those tweeting most and using the tag), languages and in the commercial version, more detailed analytics. They currently have quite a lot in Beta mode, and you can see an example of that below, and they're busy signing up people to get involved with their program. It's a really nice tool and if you're a keen Tweeter, something you should check out.