The first sentence is old eyes, which means that he is old, but the mountains and rivers he sees are all new, which means that his mental state is very good, his eyes can keep up with the times, and he can see things with new eyes, instead of standing still because he is old and selling his old.
The second sentence, heaven and earth are more energetic in the snow, which also echoes the first sentence, indicating that the mental state is very good, and it is estimated that the season for writing poetry should be winter.
The third sentence, hehe, is actually a proud self-awareness, thinking that he is very capable and ambitious, that he has great virtue and power, and that people around him can understand all the virtues of his sages, just feeling a little "How can a sparrow know the ambition of a swan?"
The fourth sentence has two meanings, one is to echo the world in the snow ahead, indicating that it is deep winter, and the other is to be clear-headed. If there is no winter, where will spring come from? In other words, if winter comes, can spring be far behind? From the understanding, that is to say, although the author is frustrated in life, work or career, the time to show his talents will come soon.
On the whole, it is a poem that encourages and inspires oneself.