You've moved around, but how do you see what's actually inside a directory? That's where ls comes in — the single most-used command in Unix. You'll type it hundreds of times a day once you get comfortable.
List files — ls
Plain ls shows you the names of files and directories in your current location.
$ ls
Desktop Documents Downloads Music Pictures
Simple enough. But ls really shines when you add flags.
ls -l — long format
Add -l and you get the detailed view — permissions, owner, size, and modification date.
$ ls -l
drwxr-xr-x 2 you you 4096 Jun 15 10:30 Documents
-rw-r--r-- 1 you you 142 Jun 14 09:15 notes.txt
That first column shows the file type (d for directory, - for regular file) and permissions. The numbers after are the file size in bytes and the timestamp.
ls -a — show hidden files
Files starting with a dot are hidden in Unix. ls -a reveals them.
$ ls -a
. .. .bashrc .profile Documents
Notice . and .. always appear. Hidden files are usually configuration files — .bashrc, .gitconfig, .ssh.
ls -h — human-readable sizes
Combine -h with -l to get sizes in KB, MB, GB instead of raw bytes.
$ ls -lh
-rw-r--r-- 1 you you 1.2M Jun 15 10:30 bigfile.zip
Much easier to read than 1234567 bytes.
Combining flags
You can combine flags however you like. The most common combo is ls -la — show everything, detailed view. Or ls -lah for the full picture with readable sizes.
$ ls -lah
total 28K
drwxr-xr-x 4 you you 4.0K Jun 15 10:30 .
drwxr-xr-x 8 you you 4.0K Jun 14 08:00 ..
-rw-r--r-- 1 you you 220 Jun 14 08:00 .bash_logout
-rw-r--r-- 1 you you 3.7K Jun 14 08:00 .bashrc
-rw-r--r-- 1 you you 807 Jun 14 08:00 .profile
This is the view I use 90% of the time. Get used to typing ls -la — it's muscle memory for every Unix user.