If you found this phrase on a site like Thingiverse, Printables, or a modding forum, it refers to a replacement shell or cover.
The PlayStation 4 (PS4) is more than just a box for discs; it’s a central hub for a vast ecosystem of interconnected devices. When people search for a they are usually looking for ways to bridge their console with other hardware, like smartphones, the PS Vita, or PCs. ps4 link
: Use your phone’s keyboard to type messages or search for content on the PS4, which is much faster than using a controller. If you found this phrase on a site
Here is a breakdown of what that phrase usually describes: : Use your phone’s keyboard to type messages
The Ultimate Guide to "PS4 Link": Connecting Your Gaming World
The man smiled. "Remote Play is a two-way street, sweetheart. You’ve been broadcasting your home IP to the same PSN lobby for 1,247 days. I didn't hack you. I just… walked in."
It is worth noting that Sony recently released a "PlayStation Link" wireless technology for the PS5 (Pulse Elite/Explore headsets). However, since you specified , this is likely a terminology crossover where someone is referring to the AUX Port as the "Link" port.