Kanji refers to the Chinese charcters imported to Japan which can stand for any number of Japanese syllables written in hiragana.
(Whoever's reading, you have the remaining 4 mins 45 secs to explain the origin, the evolution, the 6 Warring States' scripts, the 8 Qin scripts, the 6
Han scripts, the 6 principles of character formation, the 8 strokes of calligraphy, the rebus principle of non-sense words, the 108 rhyming categories, go'on, kan'on, tou'on, kun'yomi, kokuji, simplification, the 6,000 JIS characters, and the 80,000 non-JIS characters, and the evolution into Manyo kana, katakana, and hiragana. Thank you.)