If a kid wants to go to play for another school for any reason, they can notify the school that they are going to enter the portal. Their name then shows up inside the portal for all other universities who are looking for players at that position. The player can then choose to accept any of the offers that come through.
It's nothing complicated. It's just a streamlining of the transfer process that carves out exceptions to the old rule about losing a year of eligibility.
The QB for 11-1 Ohio State just entered the portal earlier this week, likely because he doesn't see the point in playing a worthless game at the Cotton Bowl.
The most important part of the transfer portal is that it turns all the kids into free-agent mercenaries, and means that college football is fully and officially just a farm league for the NFL. It no longer resembles anything that is remotely connected to amateur athletics.
thanx