You Want An Exclusive Emote
If you want access to an exclusive emote for your character, you'll need to pick up the Season Pass.
The Season Pass will net you a "Shoot First" emote to use in the game. Emotes allow your character to express him or herself in the game. It's not an essential item but some people love them and want to collect them all.
We wouldn't buy the Season Pass for the emote alone but it's a nice little bonus on top of the other content that comes with the DLC. And the Season Pass is the only way to currently get it.