vCalendar files are a way of automatically adding meetings to your electronic calendar, they can be read by many email clients and mobile devices.

When you click on Download Selected below you will be asked to Open or Save the .vcs.
If you have a recent version of Microsoft Outlook, for example, you will be able to select Open and view the details of the selected meetings before saving to your Calendar.
If you are not presented with the option to open the file you may have to select Save and then use your client's Import option to add the meetings to your calendar

Please refer to your software provider's documentation if you need further assistance