Why do you need to block an IP address in WordPress?
Every day, every server with a public IP — which is to say almost all of them — and every domain is hit by thousands of attempts against the login page, or against files in folders where attackers know of bugs and flaws they can exploit to take over a site, or an entire system.
Unless you are a system administrator, or you install a plugin that tracks incoming traffic to your WordPress pages, there is practically no way to find out this is happening. Most people have no idea that every machine online is constantly probed by bots: they ping it, scan for open TCP ports, look for files with known vulnerabilities and, above all, hunt for website login pages.
Stopping those attempts before they start is the best way to protect your servers and your sites. That is part of why Deskmode Pro exists: to show you at a glance who tried to reach your pages, and when.
Keeping out of the login anyone with no reason to be there — better still, allowing access to the WordPress login page only from the country where your administrators are — is the most effective way to safeguard your site.