SPAM is often created by a bot rather than a human, one way for your WordPress website to distinguish between the two is to install a CAPTCHA plugin.

Log in to your WordPress admin area.

Go to Plugins, then click Add New.

Enter "CAPTCHA" in the 'Search Plugins' box

Click on the name of the plugin to learn more about it

After locating the plugin you prefer, click Install Now

Next steps: After installing a CAPTCHA plugin it will need to be activated.