This means you can play your Steam games on a PC not tied to your network. The new Steam Link Anywhere extends the Steam Link functionality, while a sockets API makes it easier for developers to offer secure connections.
Steam Link Anywhere is in beta right now and users can download Steam Link Beta 688 to give it a try.
The Steam Link app launched on Android almost a year ago, but there were some restrictions with it. Sony's PlayStation Now software streams a library of games from Sony's server to the PS4 and PC, while Microsoft has been hyping its upcoming xCloud software that will stream games to iOS, Android and, according to some rumors, even Nintendo Switch. Go to the Steam Link computer settings and select "Other Computer". You can do this at the computer itself or you can use a remote desktop app to do it from wherever you might be.
Valve's announcement of Steam Link Anywhere was pretty short and sweet. For both the host PC and the Android device. However, my T-Mobile data connection at home wasn't fast enough to actually play anything, but I was able to get connected. For Android users you need to be on the beta version that is from March of this year. Valve explain the system here, and among the perks for developers are anonymized network traffic (protecting servers and clients from DDOS attacks) and potentially lower pings through Valve's networks.
Steam Link was originally released as a hardware device in 2015, but Valve later discontinued it in favor of an app for mobile devices and smart TVs.