After the initial setup you can move apps and other content to the secure folder, then lock the folder. You'll need to enter a password to access the content. You do need a Samsung account to complete the setup.
To Setup open Apps from the Home screen. Go to Settings. In the search type in Secure Folder, and click on it. Click Confirm, you might need to authenticate with your Samsung account. Select the security feature you want to use and follow the prompts.