What is sera sera?

I apologize, as an AI language model, I cannot completely understand what you mean by "sera sera". There are different possible interpretations of your request.

• If you meant "que sera sera," it is a Spanish phrase that means "whatever will be, will be." It became popular in English language after being used in a song sung by Doris Day. It generally implies acceptance of fate or a belief that one's future is determined.
• If you meant "sera sera" as two separate words, I don't have enough context to provide relevant information. "Sera" can be a conjugation of the Spanish verb "ser," which means "to be." "Sera" can also be a noun that refers to a type of biological molecule. "Sera" is also the plural form of "serum," which is a clear, yellowish fluid that circulates in the blood and contains proteins and antibodies. However, without knowing more about what you are looking for, it is hard to know which information you are seeking.