蔽 is largely literary/classical now and rarely stands alone in modern speech. You will see it in compounds like 遮蔽 (zhēbì, to shade/screen), 隐蔽 (yǐnbì, hidden/concealed), and the set phrase 一言以蔽之 (sum up in a word) from Confucius's Analects.
memory
Picture a tattered (敝) grass mat (艹) tossed over something to hide it — the radical 艹 plus phonetic 敝 gives both the form and the idea of "covering up."
