Select the exchange and contract, to enable the filtering select the "filter on" check box and specify a date range or relative span.
Briefly, the plots will show the termstructure of implied volatility over time to expiry, over time. The dots indicate the actual expiration dates of the contracts. The first and last curves in your range will be labeled with expiry dates. help   hints
This a plot of the implied volatlity of the option versus time to maturity. The implied volatility is the approximate 100% moneyness.
The Y axis is the implied volatlity from either the Black, BaroneAdesi or Bachelier model-it is the approximate 100% moneyness.
The X axis is defined as the time to expiry.
There are a lot of listed skews, sometimes there is no trade or only one strike is active. You may see and empty plot because of this.