The whole sentence in Jianghai * * * is: "The mountains and rivers are far and wide, and the fireworks on earth are yours, not yours", which means that there is no one that is not yours, and there is no one that is not yours. Everything looks like you, but not you. Write the author's yearning and ambivalence towards the right person.
The vastness of mountains and rivers depicts a magnificent picture of natural scenery, with a magnificent beginning. The fireworks on earth depict the lively atmosphere on earth.
The sentence "the mountains and rivers are far and wide, and the fireworks on earth" summarizes all the scenery seen by the author and paves the way for the following two sentences: none of them are you, which means that what you see is not you, but you are only in my heart.