The Twitter terminology, like any made up terminology, takes a bit of effort to learn.  A few terms for you;

Twitter - the company, the application

Tweet - a broadcast message sent over the Twitter application

Tweets - more than one Tweet

Take Me to Your Twitter Leader

Twitterers - people that tweet

Tweeple - twitter friends

Followers - Twitterers that subscribe to read read your tweets

Friends - Twitterers that you subscribe to so that you can read their tweets

RT – re-tweet. Sending along someone else’s tweet that you read and liked, often adding a comment

Hashtag # – Adding the # character to any set of characters makes them search-able. Widely used at conferences.