Final answer:
Backing vocals enhance a song with a blend of harmony, contributing to a richer sound, and texture, adding depth with vocal layers.
Step-by-step explanation:
The backing vocals in a song are typically a mixture of harmony and texture. Harmony is created when backing vocals sing different notes that complement the main melody, resulting in a richer and fuller sound. Texture, on the other hand, comes from the vocal timbres and the way the backing vocals are arranged and layered, which adds depth and complexity to the music.