You can add new keywords to existing tracking with an option to tag them. Duplicate keywords will be removed automatically.
Position history chart represents the rankings position over a period of time for a selected keyword only.
The list of URLs for a selected keyword gives you an idea of what URLs give keywords that rankings and the estimated visits that come from this URL.
The chart displays the search volume numbers per month for a selected keyword and gives you an overall great representation of how good this keyword is, how much users are searching for it, whether it is a popular keyword or not.