警告 + 说 + Clause
警告 (jǐnggào) means "warning" or "to warn" and can function as both a noun and a verb. As a noun, it refers to a formal caution or admonition. When followed by 说, it introduces reported speech, meaning "warned that…"
老师给了他一个严厉的警告。
Lǎoshī gěi le tā yīgè yánlì de jǐnggào.
The teacher gave him a stern warning.
政府发出警告说台风要来了。
Zhèngfǔ fāchū jǐnggào shuō táifēng yào lái le.
The government issued a warning that a typhoon is coming.
她警告我不要一个人走夜路。
Tā jǐnggào wǒ bùyào yīgè rén zǒu yèlù.
She warned me not to walk alone at night.