You can start by connecting your Gmail account to any desktop email client that supports it. Once you are done, all the folders you have created in Gmail also sync to the desktop. Not all the desktop email clients do that but the good ones will definitely sync them. This may not be a good thing. All the email clients may have an “all messages” or some similar named inbox where each email appears. If you wish to exclude some Gmail folders from synced to client them you can. There is a setting that lets you hide Gmail folders from the desktop email client. The setting is in the Gmail so it doesn’t matter which one email client you use.
Hiding Gmail folders
Start by opening the Gmail in your browser, click that little cog wheel button under your display picture, a menu will appear, select the setting from the menu. In the screen of settings, go to the labels tab. The default folders will be listed at the top so if you wish to hide any of them, Uncheck show in IMAP option. If you wish to hide custom folders, scroll down the screen and you will see them. Each one will have its own show in the IMAP option.
The folders in the Gmail are not the actual folders. They are basically labels to add to your messages to keep them organized. If you go to the label, you will find marked messages there but deleting it will not delete any of the messages. Even if you hide the folders, messages are not going to be removed from the email client. The labels will be there in Gmail even if you hide them from the main email client. If you want to hide them from Gmail. You may still do this from the same screen. Each of the labels will be having a hide option, clicking it will hide it from the left column in the Gmail, but none of the email messages will be hidden or deleted. The label will not appear, but the message will be readable. If you use the Hangouts in the Gmail, chats are saved to their own folder.