If you take a picture with the Samsung Galaxy S5, then this is replaced by the file name the date and time at which it was recorded. Would you like to send the image and thereby change the file name of the image, then you should this article help:
Image on the Samsung Galaxy S5 Rename: To do so, first open the menu and then the Gallery app. In this Now please search for the image whose filename you want to change. Did you find this, touch it so that it is displayed in full size. If Sienun tap the top right of the symbol with the three points, then a small menu, which now can be in "Rename" selected appears.
You can then rename the file name of the image in a new window. About the same button the image will be saved. You now know how to rename photos to the Samsung Galaxy S5.