How can I make a new folder on GitHub in 2021? I have looked at other topics about this and they all contain something about the “GitHub Interface”. I have no idea what that is or means.
How can I make a new folder in my repo without using the “GitHub Interface”? Even if there is no other way to make a folder besides using the Interface, how do I go into the interface?
Please and thank you ; Have a good day and thanks for your answer, if you do answer my question. 
The “web interface” means just the things like buttons, text fields, and so on provided on the website to work with it. 
When creating a new file on the GitHub website you have a field for the name. You can just type a slash (/) to separate directories. So if you type folder/test.txt you’ll get a file called test.txt in a folder called folder. 
You cannot add empty folders. That’s a general Git limitation, not specific to GitHub.
yup that’s the exact answer above, in GitHub Web, simply type the name of the folder then type /, and create a file just like temp.txt. Later, when you have the actual file/s, just delete that. GitHub Web does not allow empty folders.
Now, the same is also true when you want to delete a folder, simply delete everything inside that folder and the folder will be automatically deleted too.