I don't understand File Explorer.

Windows gives you several ways to view your files. They are the same files, just presented to you in different ways. Pick whichever way you like.

The cloud is just another way of saying the internet. In all operating systems, you have the choice to store some or all of your files on your computer or on the internet, i.e., 'in the cloud'. Again - pick whichever way you like.

No matter how they are presented to you, the files themselves are stored in special folders that Microsoft setup long ago to store your files:

C:\Users\your user account\Documents

C:\Users\your user account\Downloads

C:\Users\your user account\Music

C:\Users\your user account\Pictures

C:\Users\your user account\Videos

If you are syncing files to OneDrive, the files that you are syncing are stored here:

C:\Users\your user account\OneDrive\Documents

C:\Users\your user account\OneDrive\Music

C:\Users\your user account\OneDrive\Pictures

C:\Users\your user account\OneDrive\Videos

The cloud is good for keeping files in sync on multiple devices. To avoid having old file versions in OneDrive, it's best to free up local storage space on these devices and access only the cloud archive.

Using Files On-Demand ensures you access the latest versions of files.

https://www.youtube.com/watch?v=UzIA9uykIhE&t=43s

Thanks for posting here in Microsoft Community, I understand that you are having experiencing confusion and uncertainty about Windows File Explorer’s layout and navigation views, to better understanding when you see the same‑named files appearing in Home, Personal, Desktop, and this PC, have you checked the full folder path shown in the address bar to confirm if they are actually stored in different locations, or do they all point to the same underlying storage folder?