Ls

ls is the basic "LiSt me the contents in the filesystem" command used in a unix shell. It operates on the current directory by default, and displays a list of all files, directories, named pipes (FIFO), sockets, symlinks, and devices.

There are many, many options to ls, and they can vary greatly from system to system. Check the local man pages for details. You want to install gnuls if you want ls with colour.

$ ls -lart

is a popular usage with arguments. A long listing which shows .files, reversed by time. You can alternatively shell:alias this if you use it a lot.