Synesthesia

I read the other day that Beyoncé has something called Synesthesia. Cross-wiring? Please help me understand what this is.

Typically, in the human brain, colors and numbers tend to be experienced as separate categories and are processed in discrete neural networks. Synesthesia is a neurologic phenomenon involving the conscious processing of multisensory stimuli. The brains of Synesthesiacs tend to process these ordinarily separate categories in the same or overlapping brain areas. Immersing oneself in one of the senses tends to stimulate associations with the other senses. Even microscopic changes in brain wiring can lead to different realities. Many well-known composers, musicians, artists, writers, and so on reportedly are Synesthesiacs. The list includes names such Duke Ellington, Nikolai Rimsky-Korsakov, Billie Eilish, Lorde, Kanye West, Billy Joel, Franz Liszt, Carol Steen, Itzhak Perlman, Jean Sibelius, Leonard Bernstein, Richard Wagner. Van Gogh, Marilyn Monroe, Edgar Degas, Charli XCX, Eddie Van Halen, Stevie Wonder … More tomorrow.