excel公式簡化請教_關於IF &CHAR(10)

如題,有個excel表格如下圖，我目前理解的意思是：
在M~X欄位中讓某月份填入完成日期並讓該儲存格背景呈綠色後(例如4/22)，
在C欄位就會顯示"4/22 Pass)

C欄位帶的公式為：
=IF(JAN=43,"1/"& M5 &" Pass" &CHAR(10),"")& IF(FEB=43,"2/"& N5 &" Pass" &CHAR(10),"")& IF(MAR=43,"3/"& O5 &" Pass" &CHAR(10),"")& IF(APR=43,"4/"& P5 &" Pass" &CHAR(10),"")& IF(MAY=43,"5/"& Q5 &" Pass" &CHAR(10),"")& IF(JUN=43,"6/"& R5 &" Pass" &CHAR(10),"")& IF(JUL=43,"7/"& S5 &" Pass" &CHAR(10),"")& IF(AUG=43,"8/"&T5 &" Pass" &CHAR(10),"")& IF(SEP=43,"9/"& U5 &" Pass" &CHAR(10),"")& IF(OCT=43,"10/"& V5 &" Pass" &CHAR(10),"")& IF(NOV=43,"11/"& W5 &" Pass" &CHAR(10),"")& IF(DEC=43,"12/"& X5 &" Pass" &CHAR(10),"")

請教一下：
Q1 這個公式的意思是什麼,尤其小弟開頭就不懂月份JAN=43的意思
JAN=43,"1/"& M5 &" Pass" &CHAR(10),""

Q2 C欄位的公式好長,有沒有更簡短的公式可代替呢?