A target is the URL of a web app or site. All the following are possible examples of targets:
The target is the scope of the scan. The scanner will never leave its scope, i.e., it will never scan any page that is not under the target.
If the target is https://example.com, the scanner will not scan, for instance, www.example.com or any other hosts. In other words, the scanner will only scan URLs that start by example.com.