The V device worn on Army Commendation Medal and other awards, stands for 'valor.' Joining the V are two new devices: the 'C' and 'R' devices, where C denotes 'combat' and the R means 'remote.' Both are described fully in Military Personnel Message 17-095, titled 'Implementation of Department of Defense Guidance for the Newly Established 'C' and 'R' Devices'. The combat C device is earned 'through service or achievement under combat conditions.' The intent of the C device is to distinguish a particular award as having been earned in combat. The remote R device is rated when 'a Soldier remotely, but directly, contributed to a combat operation.' For more details, see this Military.com news article.
For more on military medals and decorations, see this Military.com section.