How to block unwanted ads from my S7?

I bought my first smartphone recently, an S7.  It bothers me that I get calls and when I swipe the screen there's an add in the lower half of the screen telling me call some number for  "best insurance" or whatever. I don't even see any clear "X" or way to dismiss it.  Or sometimes unsolicited videos start playing in that area. How can I block all  this stuff?

Thanks