Bhagavad Gita Yagya involves an offering to the divine fire (Agni) along with the reciting of the verses from the holy Bhagavad Gita. Bhagavad Gita is based on teachings from the divine mouth of Lord Krishna to his friend Arjuna, and these teachings can not be explained in a single paragraph. By the way of the Bhagavad Gita Yajna, the Yajman (for whom the Yagya is sponsored) feels the teachings and philosophies of the Bhagavad Gita. Bhagavad Gita Yagya explains all the qualities of good human life and all the paths that lead to Moksha (salvation). It is a practical guide to life and guides us about how we should think and act in any situation and how to spend our life. In this era of Kalyuga, one needs divine teachings that lead us to the right path and remove ignorance and darkness from our minds. Also, to achieve the ultimate goal of salvation (freedom from the cycle of life and death), one must perform activities that help one achieve Moksha. Bhagavad Gita Yagya is a great way to fulfill these objectives.
Also, the Yagya helps in achieving peace after death. This is why YagyasDevam.com highly suggests Bhagavad Gita Yagya for your beloved departed souls so that their souls rest in peace.