Until now, there were two ways to save content in TYPO3. With each of these options, you had to click two buttons in succession. With the new save and close button, this is now easier.
If you use the new save and close button, the TYPO3 backend performs two functions, saving the changes and closing the element at the same time. This means that in future you will no longer have to click two different buttons in succession to complete your changes in the system, thus making your work in the system easier.
Try out the new function, it's worth it!