A folder in Engpsh is usually referred to simply as a "folder." You can use the phrase "folder on your computer" or "folder on your hard drive" to specify that you are talking about a digital folder, as opposed to a physical folder for storing papers or documents. Here are a few examples of how you might use the word "folder" in a sentence:

"Please save the document to the 'Reports' folder on your desktop."
"I can't find the file I need. Is it in the 'Invoices' folder?"
"Let's create a new folder called 'Project X' to store all of our project-related documents."