The "Mask" is a sculpture of her face. It's a play on the album title which is based off of a Chinese "hanja" character for her real name. During an interview, I think on Jessi's Showterview, Solar said Spit it Out meant she was spitting out/showing off her passion. While Solar is a vocal powerhouse. She has some very impressive vocal control as well. Her solo stuff is mostly about showing her ability even when she isn't just sheer power.