Lists the directories and notes here. Everything it prints is a link, so you can click instead of typing.

-l names the owner and the mode, which together are the answer to what you may do with a thing and why: see man sh, and man chmod for changing them. A note is measured in the time it takes to read, and everything else in bytes.

The time is when the thing last changed, in the shape ls prints one: the time of day while that is still the useful part, and the year once it is not. Everything that came out of the Nix store is dated Jan 1 1970, which is not a mistake here or on the machine this is pretending to be: the store normalises timestamps so that a build is reproducible, so half of a NixOS system is dated before Unix. A note you have changed is measured in bytes too, and listed in the colour of things that are only here.

Given a file rather than a directory, ls lists that one file, which is how you look at its mode. -a shows the names beginning with a dot: there are some, and they are not all yours to read.