Signese

answear:

1,万涓成水 was come from this poem:万涓成水汇大川，千转百回出险滩。滔滔长流济斯民，力发黄河第一湾。

万涓成水:涓=stream 水=river. so it means: (even) a great river was formed by the many streams who have joined in together.

as for 万涓成水，汇绿成和 was from a slogan：万涓成水，汇爱成河. 河means a large force here. so the original slogan was trying to tell people, that if we gether love and care from each and everyone of us, it will become a large force just as a mighty river was formed by tens of thousands of tiny streams.

2, the words in ur picture means: just like a mighty river was formed by tens of thousands of tiny streams. if everyone in this society is helping to improve our environment （by plant and take care of the public greens）, the dream of making a harmonious society shouldn't be too far to reach.