I play- it's kind of like a slice-of-life, LA women in their forties, playing forty kind of what's their friendship like, and what's their life like and so I just play one of the four friends.

This quote is referring to a play (or perhaps a movie or TV show) where four friends in their forties are living in Los Angeles. The quote suggests that the play focuses on their friendship and their lives, and the person speaking plays one of the four friends. In other words, the play is a representation of what those four friends’ lives are like in Los Angeles and their relationship with each other.