The skin is completely free, and there are easy steps you have to follow in order to get it. Additionally, the skin, which is being called BP-1 is currently available only for Pathfinder. In order to get the skin, you have to log on to your Apex Legends Account on either Xbox One, PS4 or PC between December 3 and January 14.
Source: N4G PC Apex Legends is giving away free Star Wars Skin for a limited time.