the.com/bars
Where rhymes are measured, drinks are poured, and prisoners count their days.
means In slang, exceptionally skillful rap lyrics — though it also means a drinking spot, a unit of pressure, or what keeps you in a cell.
from From Old French barre, a rod or barrier; the musical bar marks rhythm, so rappers' lines became measured in bars.
Pressure unitOne bar roughly equals Earth's sea-level air pressure.
Rap mathMost verses run sixteen bars by convention.
Behind barsIron rods named the cells they confined.