I tried to read here, for example, but I misunderstand what is Page Hijacking. I saw we don't have a session on this.
What is page hijacking?
I don't really support the definition given in the link you provided.
Page hijacking suggests a third party takes over some critical functionality of your site, like your login page or your checkout page. On the other hand, it is also a term used to describe the set up of a copy of a site to trick the users into sharing critical information.
I think it comes down to two general scenarios (and I would love anyone with more knowledge on the subject to propose corrections or additions):
A malicious third party sets up a site that is identical to the one they target. Then they use various techniques to ensure the user will end up in their own version of the site than the intended one. Once there, the user can not discern between the original and the copy so they proceed to do things they would normally do, like insert their credentials, personal information, buy stuff. This information / money is directed towards the third party that set up the copy.
A malicious third party manages to replace part of the site with a copy they made. For example they modify the "login" button and make it direct to another login form that they actually made, or they manage to insert a piece of malware and have it run in the background of the legitimate site.