That's the lockscreen, right? So you're getting multiple notifications across multiple platforms from that same "click-now-on-this" junk? Or is that just one big popup ad?
When you get one, swipe down the notification panel and long-press the notification, then tap App Info. Which app does it say is giving you the notification? If the notification claims to be from Facebook, does the App Info option confirm that it's Facebook?
It's most likely the notifications you might have turned on for some websites inadvertently. Follow the steps below.
1. Long press the notification that bothers you, you will know which app is actually sending you notifications.(it is highly likely that this icon is fake, not from the actual Gmail or Facebook app).
2. If it is a browser, then go to site notification settings of that browser. And remove all sites that you don't know or which you don't trust. Also for the sites that you don't want notifications from.
Second possibility is that you might've installed an app which is an ad-ware(which posts adverts in form of links, notifications popups, banner ads etc.) or malware (apps that are intended to perform data thefts and a lot of other things by malicious attempts).
Again,
Step 1 from above will tell you which app is sending you notifications. This app really doesn't seem trustworthy. My personal recommendation is that you should uninstall this app immediately.