G_s_Smooth_Modern_HD_v2.03.zip is a release file of the Minecraft resource pack G's Smooth Modern HD [256x]. It was published on July 26, 2012 and is 160.3 MB in size. For the full description, screenshots and every other version, visit the G's Smooth Modern HD [256x] resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.