When you have a blog then you want to know the performmance of your blog, that is why you want to monetize it. You want to know how much traffic you get to your blog and how many clicks you get on ads and links. There are different free advertising services that you can use, and maybe the one that is most kknown might be Google Adsense.You can set up your adsense sccount here, you only need a free Gmail account to sign up with. The you must follow the steps inside to be able to get your blog approved to use adsense advertising on. You need to enter your blogs url adress and you need to put a code given by Adsense on your blog. Now there is a free plugin called site kit that simplifies this process. Thios plug in automatically ads the adsense code in the correct place on your blog. You can search for this plug in at wordpress.com Then you must check out the rules Adsense have in order for you to get your blog approved. You can find information on what you need to do inside Adsense. They also have a forum there where you can ask any question.
Now during these special times that we have now you may have to wait longger to get notified if Adsense has approved your blog or not. Because they do not have so many staff working now during these times of the corona virus. But you can still get approved by Adsense and make money with their ads and at the same time monetize your blog. Best of luck.