Neither I nor Google are aware of a standard called "HD Printable".
The only technical definition of "HD" is for TV - and that means anything over 720p (1,280×720). But that's under 1 megapixel so I doubt they mean TV-level "HD".
You need to know how many pixels they want. At highest resolution in 4:3, the S7 Edge camera takes 4032x3024 pixel images. So it can print an 8x10 image at approximately 375 PPI with no scaling (just a little cropping) or a 56-inch by 42-inch print at 72 ppi. Of course, the standard JPEG format is hardly lossless, so as chanchan05 said to make the most of the camera if they really want to use all the pixels, you're going to want to set your phone to save RAW images and then convert (or have them convert) them to a lossless format.