Short Answer: The entire movie is set in a Food Court/coffee shop. The poster is showing some of the props used by Kali from the movie. It is showing the items arranged on Kali's (Kajal Aggarwal) table.
The First Look poster gives a glimpse of props possessed by Kali with her. The poster shows a coffee cup in the center surrounded by different objects like Bhagavad Gita, rose petals, Pistol, chits.
The film starts with Kali, a troubled woman thinking about something in a coffee shop. The story is spun around the events happening in the foo court. All the main characters shown in the film are related to this Food Cart. Either they work there or visit that place. So, the coffee cup symbolizes the location the movie takes place i.e., a coffee shop.
As we move forward in the film, we come to know that the posture has used some of the items Kali has with her. They are Bhagavad Gita book, a Pistol, an organ donation form. In the beginning, she plucks petals from a red rose thinking "Do it, Don't do it". She gets an option to do it whatever she was thinking to do. She determines to do it and signs an organ donation form. Plucked rose symbolizes that her life which is also full of troubles.
Bhagavad Gita shows her relation with God. Through her life, she realizes that every human being has Good and evil in them. Good is shown as the representation of God and the ghost shown in the film represents evil. Hence, the Bhagavad Gita shows her faith in God.
Kali somehow gets a pistol and tries to use it against herself. At the end of the movie, she says that she wants to commit mass murder and she won't regret by doing that. The same pistol was shown in the poster.
The decision she was taking was about committing suicide. She says it is a mass murder because all the main characters shown in the film were reflections of herself as she was suffering from psychological issues like Dissociative identity disorder, child abuse and other. By mass murder, she means she's killing all the personalities inside her.
By watching the film, we will know that these props also relate to different characters or the episodes take place in the film. Each character is an aspect of Kali's life.
Chits: These shows the situation about making the choice which Chef Nala was in.
Pistol: Meera and her boyfriend using illegal ways to earn money.
Coffee cup: The main theme of the film i.e, a food court or a coffee shop. Either We can also say that the cup symbolizes the old man who visits the coffee shop daily and orders the same.
Rose petals: Red rose represents Radha (Regina Cassandra)'s love story. Fallen petals symbolize Kali's situation which is in troubles. These are formed when Kali plucks off all the petals while making some choice.
Bhagavad Gita - Shows the faith of little girl Moksha towards God.
Organ Donation form: It is the form taken by Kali to donate her organs to the needy after she commits suicide.
So, the posture was designed in such a way to represent each main character with some object related to them. At the same time, importance was also given to Kali, the protagonist by showing objects on her table.