Example sentences
zǎo早shàng上hǎo好！
Good morning!
tā他zǎo早shàng上qī七diǎn点qǐ起。
He gets up at 7 in the morning.
About this word
早 is early, and 上 works here as a suffix meaning in or at, the same one you hear in 晚上. 早上 is the early part of the day, roughly dawn until about nine. 上午 is the forenoon and runs up to noon, so the two overlap less than beginners expect. 早上好 is good morning. Learn the set as a block: 早上, 上午, 中午, 下午, 晚上.
The story behind the character
早
早 is 日 (sun) with 甲 below, worn down over the centuries into a plain 十. Xu Shen wrote 早，晨也。从日在甲上, the sun on top of 甲. 甲 is the first of the ten heavenly stems, the beginning of the count, so the two parts together read as the first moment of the day. 早上 is that hour, and also morning in general.
上
A line with a short mark above it, meaning "on top of." This kind of character isn't drawn, it's indicated. Xu Shen wrote 上, 高也: "up, high." Fun fact: it used to be two lines, and the vertical stroke was added later to stop it being confused with the number 二.