What does it mean that peach blossoms set each other off in red?

"Peach blossoms set each other off in red" means that I saw that beautiful face and peach blossoms set each other off and looked particularly rosy.

The poet came up with an image that is still familiar to people-peach blossom. Everyone knows how gorgeous the peach blossoms are in the spring breeze, but the "human face" can "reflect" that the peach blossoms are particularly red, and the beauty of "human face" can be imagined; Moreover, the already beautiful "human face" is more youthful and beautiful against the bright red peach blossoms. A dazzling "red" word, it is strongly rendered this scene and atmosphere.

Source: Titu City Nanzhuang

Cui Hu in Tang Dynasty

Last spring, in this door, the girl's face contrasted with the peach.

Today, I came here again. I don't know where the girl went. Only the peach blossoms are still there, smiling in full bloom in the spring breeze.