Origin

The kanji 碑 combines stone (石) on the left, which establishes that this character refers to something made of stone, with a sound component (卑) on the right that hints at the pronunciation. Tombstones and monuments are typically carved from stone and set up as lasting memorials, so the stone component makes sense for the meaning. The right component doesn't contribute to the meaning—it simply helps indicate how the character should be pronounced. Together, the character literally pictures a stone object used for commemoration, which is why it means tombstone or monument.