Both
At it’s best, it’s factual information: "We will be having a sale on Dec 15th from 9-6 PM at [address]. Take [directions]" or "If not satisfied, return for full refund" (assuming that those are accurate).
But it’s always full of at least soft lies: pictures of burgers that you’ll never eat, birds flying on beautiful days (so what?), beautiful fit people drinking Duff beer, people happy with Brand X but grimace using Brand Y, "We’re the best, you’ll love us", "plus shipping and handling" which turns out to be a major hidden charge, etc.
Even facts can be misleading: "Contains no trans-fatty acids!" implying that it is good for you, but it is loaded with other grease and sugar.