=IF(ISERROR($P12),"",IF($P12=$P$7,INDEX($J$2:$N$26,MATCH($P$7,$J$2:$J$26,0)+$O12,Q$8),""))
请帮我详细说明这个公式的应用含义,越详细越好,我看着都晕;谢谢大侠们