If your owner rank becomes level 2, you can start using the pig plaza.
If you put your pig into the truck, you can choose whether to "ship" or "go to plaza"
If you bring your pig to the plaza, the gender will be separated.
A piglet will not be able to go to the pig plaza.
A pig will not continue to grow if it's in the pig plaza.
It will re-start growing when you bring them back to the pigsty.