From Beyonce's "Irreplaceable" ,

1.) Dismissed, dumped, broke off

2.) "Step aside," as in when a person is dumped: means to get out of one's face and life so that a new partner can be established.

3.) Indicating where the door is located, even if it is not actually located to the left -- "To the left" indicates that your exit is expected right fucking now.

BF: Baby, it wasn't me with that girl!
GF: Ain't got time for your excuses, playa.... to the left.

Now, I understand the song.. thanks urban dictionary!