If footer had at least one element, this might be the one. The year and the copyright symbol. This is a way how to protect your website from plagiarism.
In WP Admin Panel, go to => Appearance => Customize > Footer copyright settings
Here you see will Copyright text section where you have to put your copyright text.
You can change copyright text. The copyright notice also tells site visitors who own the website, though it sometimes also includes information about the company that developed the site or the template the site owner used. Refer attach screen shot.
1. How to change Copyright Text?
Go to => Appearance => Customize => Footer Copyright Setting => Copyright Text
Here you can find Copyright text input field, Enter your text here then Save & Publish. Refer attach screenshot.