It's just a simple, iconic hand gesture (iconic in the City of Angels), at least: thumb and forefinger of the left hand, first two fingers of the right hand, coming together to make the “LA” logo.
LA Galaxy midfielder Romain Alessandrini has already mastered the sign since arriving in Southern California from France this offseason – and it's become a way for him to connect with the city and his club's supporters after big moments on the pitch, including his goal in Orlando this past weekend.
Watch here for Alessandrini's explanation of why he does what he does: