Unless you have ads blocked in your browser, you will often see 'clickbait' appear. I have one at the moment with a picture of the singer Sting and a headline saying 'Sad news at passing of...'. It looks like a genuine news item about Sting's death. If I didn't know better, I would have clicked it to find out more and would most certainly have found that I had been redirected to a site which has nothing to do with Sting. People are paid when people click on these links, which is how people run websites at no cost.
Your IP address can then be harvested. These sites often encourage people to give email addresses and phone numbers, all of which can be sold as marketing lists, so you can expect unsolicited emails, phone calls and ads appearing on your computer.
Hope that explains what clickbait is. Quite simply, it's 'bait' to get people to 'click' on sites.