I was recently working on manjaro and I accidentally pressed alt + right, sending me to the tty screen for the first time. After a bit of confusion I managed to get back to my desktop but I’m left wondering what this tty screen is used for? Is there ever a time I may need to use it or should I just leave it alone?
For example, when your desktop environment or display manager is broken after an update. Then you can use TTY to repair the damage.
Welcome to the forum! 
GNU/Linux is a UNIX-family operating system, and UNIX is a multiuser architecture that supports multiple concurrent user logins from different users. In addition to that, at its core, UNIX is also not a GUI-driven operating system, but a character-mode system with a(n optional) graphical user interface running on top of it.
This is why there are additional ttys, and an experienced user can even start additional GUI environments in them ─ either manually, or in an automated fashion at boot time for multiseat setups.
You can use it as you would use any other terminal, and many people find that, given that the terminal was designed for text only, text is more readable when working in a tty.
That said, I personally always recommend using the tty for system updates, and while completely logged out of the GUI. That way, none of the GUI-specific shared libraries will be in use when they are being overwritten by the update process, and therefore, there are fewer chances of anything going wrong during an update.