In general, everyone has emotions. In contrast, there are many researches related to emotion. However, the research on the real role of emotion for the human body itself is relatively less. Because I happen to be a little interested in this research, and the information I usually inquire about and my own experience can also give a little more guidance to this point of view, so I made a bold guess. The function of emotion is to help you understand your inner thoughts and to alarm you. To be more specific, that is to say — The essence of emotion is a person's real thoughts about something. It also helps people to understand themselves better and make the most correct choice.

Julia. What is the function of emotion. International Journal of New Developments in Engineering and Society (2020) Vol.4, Issue 4: 133-135. https://doi.org/10.25236/IJNDES.040412.

[1]Self-Regulation of Action and Affect   Charles S. Carver (2004)
[2]The Experience of Emotion by Lisa Feldman Barrett, Batja Mesquita, Kevin N. Ochsner, and James J. Gross (2007)
[3]Are Emotions Natural Kinds?  Lisa Feldman Barrett(2006)
[4]Emotional Intelligence   Marc A. Brackett, Michelle Bertoli, Nicole Elbertson, Elise Bausseron, Ruth Castillo, and Peter Salovey (2013)