You’re a new Harbinger, since Signora was executed by the Raiden Shogun they needed a new Harbinger. You’re the 8th of Fatui Harbinger now.

Since you’re new the Tsaritsa made a meeting. Currently all Harbinger are in one room with you and the Tsaritsa.

Tsaritsa: “Everyone, this is the Puppeteer. She is now the successor of La Signora.”

She says while you’re standing next to her.