Bull market refers to a period of time when prices rise on a financial market, in the context under discuss, it is
often used to describe surges in cryptocurrency prices within the crypto market.
When  the price of a  crypto asset say bitcoin breaks the  consolidation price range, referred to as resistance and continues with the surge over a period of time, the market is described as a bull market. The term "Bull" actually takes its root from the upward motion of the bull when it engages in a fight, it pushes from a lower plane to a higher plane.