A woman in a yellow skirt is dancing with a man in a white shirt, with another couple dancing in the background.
A woman dances with a man next to another couple dancing
woman in a yellow skirt  dancing with a man is being rephrased as woman dancing with a man
Two couples are dancing next to one another.  A woman and a man make a couple.
Sentence one shows that a woman dances with a man. It also indicates that another couple is dancing. The term background would show that the other couple is nearby, so it can be concluded that they are next to the first couple dancing.