Library/Preferences folder.

The user Library folder is hidden. In the Finder you must use Go > Go to Folder and enter the name of the folder you want to navigate to. The top level of your user folder would be ~/Library There is a Preferences folder there. But this is not something you should go poking around in; that's why it's hidden.

Choose Go to Folder from the Finder's Go menu and provide ~/Library/Preferences as the path. If you're referring to one which isn't in your home folder, navigate to the folder containing Library and remove the ~/ from the string.

(252857)

Another way to get to the hidden Library folder within your home user folder, you can Option-click on the Finder's "Go" menu. Holding the Option key while the Finder's "Go" menu is show will allow the hidden "Library" folder entry to appear.

Edit: FYI, there are multiple "Library" folders on macOS. It is very critical to know which one you wish to reference. We are assuming you mean the hidden Library folder located within your home user folder since that is the most common one most users wish to access.