Import Excel data to OS X Calendar
iCal is just the old name for what is currently Apple's main "Calendar" application (referenced here). They are exactly the same thing, Apple just rebranded iCal a few years ago.

That being said, there is a relatively easy (albeit lengthy) way to go about putting an Excel file into the Calendar app. Essentially you have to export the Excel document as a CSV, and then change it into an .ics format in order to get it to work. Instead of trying to repeat what I have found, here is the original article (updated as of 2013) which says it much better than I can in this small space.