Well, the first row is is for Tracking Token, you enter the name of your tracker. The name of your tracker can be a short name or initials of 3-16 characters. Like you can use emk just an example.
And for the description, you give your tracker a description, this would be good if want to create a number of trackers. For example if you write about technology, you can create a tracker for tracking the technology hubs and the description you can use technology.
Since these trackers are for referral "Traffic views accumulate when somebody that clicked on your tracker views any Hub", you should always make use of them when linking your hubs. This is achieved by, going to the hub you want to link and scrolling to the bottom of the page, you will find the option of link to this page. Once you do this you then select the HubPages Referral Tracker you want to use. Then copy the URL and paste it where you want to create a link.
There is also a default URL tracker which you can still use.
For those who might not be aware where the HubPages Referral Tracker is, Go to Earnings, then on your left at the bottom of the box with earnings reports you will find it.