It is a page refresh or redirection to another page that occurs during the user's navigation. This refresh is usually caused by an HTML "refresh" instruction after a certain delay.
The fact that a page refreshes its contents automatically, or even worse, that the user is redirected to another page, can cause the user to lose track of his navigation and become deeply frustrated. In the majority of cases, the user will prefer a site with intuitive navigation where he is in control of the actions performed on the page.
If this type of redirection is observed, it is necessary to remove the instruction in question:
<meta http-equiv="refresh" ...>
Refresh: ...
Similarly, it may be useful to inspect the JavaScript code on the page to verify that there is no redirection caused randomly. A JavaScript redirection should preferably be triggered by a user action.