To check out your traffic, click on "my account" at the top right of any HubPages screen. On that page, you should see a list of all your hubs, with stats for how many views you have in the past day, week, month, etc., and how many comments you've gotten.
As for the score, there's no real way to know what it means. They don't reveal the formula used to calculate it, and the fluctuations don't always seem to make a ton of sense. In general, posting hubs, getting traffic, having people comment on your hubs, and other stuff like that seems to increase your score.