This means that the person who said it is "watching your back", and is there to support you.
"Watching your back" or "Got your back" means that they are in support and there to defend you if needed.
Have my back means "defend me"
Back into the fight. Could also mean back into the struggle of life.
go back in time
It means "way back when"
you will never go back to it
Vuelve a mi translates from Spanish to English to mean back to me. It is typically seen in the phrase 'Vuelve mi amor por favor' which translates into come back to me my love.
Generally speaking, the phrase "back to back" means two events which occurred next to each other, which are intended to be visited or achieved separately and independently of each other.
To put on the back burner means to delay doing something till later.
back
Sit back and enjoy it.
The phrase "crossing the Rubicon" has come to mean an irrevocable move, something you cannot take back.
A sheep fold is a sheep pen, a place of safety. The phrase is to welcome someone back after they have been away.