This episode along with The Dirty Half Dozen (2015) takes place before the events of Avengers: Age of Ultron (2015).
The title is a play on the phrase "The enemy of my enemy is my friend", meaning that people can set aside their differences and work together when they are fighting a common enemy. In this case, the "enemy" is HYDRA, and the "frenemy" is Ward, since he used to be HYDRA but is now at odds with them.
"The Frenemy of My Enemy" originally aired on ABC on April 21, 2015, and according to Nielsen Media Research, was watched by 4.45 million viewers.