क्रोधाद्भवति संमोहः संमोहात्स्मृतिविभ्रमः। स्मृतिभ्रंशाद् बुद्धिनाशो बुद्धिनाशात्प्रणश्यति ॥

krodhād bhavati sammohaḥ sammohāt smṛiti-vibhramaḥ smṛiti-bhranśhād buddhi-nāśho buddhi-nāśhāt praṇaśhyati

From anger proceedeth delusion; from delusion confused memory; from confused memory the destruction of Reason; from destruction of Reason he perishes.

In plain words: Anger leads to confused thinking. Confused thinking makes a person forget what they have learned, then they lose good judgment, and losing good judgment ruins them.