午餐 is read as ごさん (gosan) and means lunch.
ごさん
gosan
ごさんかい
luncheon party
ごご
afternoon
ごぜん
morning
うま
fifth month of the lunar calendar
ごぜんちゅう
in the morning
ごぜんさま
coming home after midnight
ごごれいじ
noon
ごぜんれいじ
midnight
ごほう
noon gun
ごごいち
first thing in the afternoon
ごごじゅう
throughout the afternoon
うまどし
year of the Horse