This achievement will unlock when you interact with any of the 32 secret terminals in the game. The terminals are computer screens that appear turned off. There are many other screens in the game that display something - those won't do anything for this.
Each section of the game has a secret terminal. Some of them require you to do something first to reveal it. When you find the terminal, you must interact with it by pressing
Each node you play is made up of a random set of the 32 sections. The name of the section you're about to play is shown as you progress through a node (Garage, Gym, Subway, Dojo, etc.). Make note of the section name before it loads, then check the video below (credit to the creator for that, not me) for details on the terminal. The video's description has timestamps to each section. Because your spawn point in a section varies, you may not be in a convenient location when you play a section. I found it easiest to look at where the terminal is before I loaded into a section and only go for it if I spawned nearby. Since you'll be playing each section a number of times in the campaign, you'll have plenty of opportunities as you play.