Glad to hear that
The cup → Partition on the drive
The staw → An empty folder
Putting the straw into the cup → Mounting
So yeah, a mounted folder can only display one partition.
So lucy and you can drink the cup without restrictions.
Now you want to drink Sprite and she wants Fanta, but there is only one cup.
We now create 2 vessels, and put them in the cup:
mkdir -pv /media/lahpyrcopa/{sprite,fanta}
Now create name cards for it:
sudo useradd lahpyrcopa
sudo useradd lucy
Now we say the first vessel can only be drunk by lahpyrcopa
sudo chown -R lahpyrcopa:lahpyrcopa /media/lahpyrcopa/sprite
and the second vessel can only be drunk by lucy:
sudo chown -R lucy:lucy /media/lucy/fanta
After some time of drinking, you are tired of drinking Sprite and want to taste Fanta, but you don’t want to merry her. You force her in the most brutal way to give access to her fanta without permissions:
sudo chmod -R o+rwx /media/lucy/fanta
o → other
+ → add
r → read
w → write
x → execute
But she doesn’t like that so she does:
chmod -R o-rwx /media/lucy/fanta
o → other
- → remove
r → read
w → write
x → execute
and said: “First you have to merry me!” Long story short thought, you both get married and she gets your family name:
sudo usermod -aG lahpyrcopa lucy
and you get access to here fanta:
sudo chown lucy:lahpyrcopa /media/lucy/fanta
Now she has access to the sprite and you have access to her fanta through your family name (group name).
That is of course not everything, but a basic view, maybe you get the point.