This saying does not have a specific deffinition but can be used whenever a bitch is bein a bitch. if shes doin somethin that pisses u off confuses u or just annoys the fuck out of u it works.
The person being referenced (1st bitch) is behaving as themselves as they normally are as a person (2nd bitch), and their behaviour is difficult to manage (3rd bitch).
A poetic opposite derivative from the phrase "a rose is a rose is a rose".
Example: No matter how much we try to change his attitude, a bitch is a bitch is a bitch.