告 is a compound ideogram and is formed with the radical 牛 on top and the character 口, "mouth", on the bottom. When 告 is used as a verb it means to tell or report. As a noun, it is defined as a report; and as an adverb it means bright, or pure white.
告 is often combined with other Chinese characters to form words such as: 劝告 (quàn gào) "advice", 告发 (gào fā) "informant", 告状 (gào zhuàng) "complain", 通告 (tōng gào) "announcement, notice", and 广告 (guǎng gào) "advertisement". 告 is also a Chinese surname.