Created by Mattel originally as a toy it eventually develops into an animated series. She-Ra: Princess of Power was soon born; Mattel wanted a cartoon that a younger female audience would watch so they created the show with She-Ra as the lead female character.
The show was much like He-Man but like said above was made to appeal to a young female audience. She-Ra was introduced at one point in an episode of He-Man as a twin of He-Man, She-Ra had been lost for quite some time and the twins had just been reunited.
She-Ra like He-Man has a secret identity that few know about, her original name and title is Princess Adora. She becomes She-Ra to battle the evil that once had control over Etheria. Princess Adora is given the Sword of Protection.
With this sword Princess is given her power to transform into She-Ra and on many episodes battles Hordak who is a horde leader on the opposing side. She-Ra joins a group called the Rebellion who is comprised of a group of warriors who also do battle with Hordak.
Some rumors would set that a remake of She-Ra, this was mentioned because of the remake of He-Man back in 2002 however it never went though.