Why are beings born? Does anyone have an explanation as to how Buddha explains the reasons as to why are beings born? What is the reason for birth?
There is no reason why "beings(sattānaṃ)" are born, there is causal for for it.  and causal for birth (jati) is Existence (bhava).  This is from dependent  origination or Transcendental Dependent Arising (pali - Pratītyasamutpāda).

Please make sure you understand the word "being" as per Buddha.  beings or sattānaṃ is a difficult term to understand.  ("being" is not the same as permanent soul).

recommendation for further study


Satta Sutta
Dependent origination