化 (huà) is the suffix '-ization':
现代化 (xiàndàihuà, modernization),
全球化 (quánqiúhuà, globalization),
城市化 (chéngshìhuà, urbanization). Take any adjective or noun and bolt
化 on the end to mean 'becoming-X'. Here
低俗 (dīsú, 'low / vulgar') +
化 = 'becoming vulgar'.
