Low Level Languages are programming languages that do not try to be friendly.
They try to be fast. Not all succeed.
Some posit that low level languages are so named for their proximity to machine code.
We tend to believe that low level languages are so named for their proximity to hell.
The lowest of the low-level languages is Assembly.
If you find yourself dealing with assembly for more than four hours, consult your doctor.
A much more common and prevalant low-level language is C. Another quite common one in C++.
In most of your experiences with PowerShell and other scripting languages, you need not concern yourself with the workings of low-level languages.