Warframe's latest update brought us Sisters of Parvos and their new weapons. I found the below video guide the easiest to follow along on how to get a Sister of Parvos and the process of how to get their weapons.
Sisters of Parvos Guide | Warframe Sisters of Parvos Beginners Guide 2021 by Faceless Beanie
There are more guides on YouTube for this part of the game, and I recommend checking out guides from MCGamerCZ and KnightmareFrame as well.