Plain ls doesn't show everything. Any name that starts with a dot, such as .bashrc, is hidden. It isn't secret, just tucked away: programs keep their settings in dot files so they don't clutter your listing.
Options change what a command does
Most commands take options (also called flags): a dash and a letter after the command name.
ls -a (all) shows hidden names too, plus two entries that are always there: . (this directory) and .. (its parent).
ls -als -l (long) prints one name per line with details:
-rw-r--r-- 1 learner learner 2400 Jan 12 09:00 beach.jpg
Left to right: the permissions (- for a file, d for a directory, then who may read, write and run it; there is a lesson on these), the number of links, the owner and group, the size in bytes, the date it last changed, and the name.
You can combine options: ls -l -a and ls -la mean the same. Add -h for sizes like 2.4K instead of bytes.
ls -lals -lh photosReading a file
cat prints a file's contents. There's a whole lesson on reading files later; for now this is enough:
cat notes.txt