和 = 禾 (grain) + 口 (mouth) — grain reaching every mouth. When everyone is fed, there is peace and HARMONY. From that warm image come both meanings: 'harmony / peace', and the everyday connector 'and'.
和 is one of the most cherished ideas in Chinese culture — 和平 (peace), 和谐 (harmony), 和气 (good-natured). Confucius prized 和 above almost all. In daily speech it's also the simplest way to say 'and' between nouns: 你和我 = 'you and me', 我和你. A character that means both 'and' and 'harmony' says a lot about a civilization.
Grain (禾) reaching every mouth (口) — everyone fed, so peace and HARMONY (and 'and').
和 joins nouns, not whole sentences: 你和我 ('you and me') is perfect, but you don't use 和 to link two actions. For that, Chinese just lines the verbs up.