Once I see from the movie that a man says he wants to be a tree, because a tree is stable and will never be flowed away. At that time, I don’t understand the meaning,

Once I see from the movie that a man says he wants to be a tree, because a tree is stable and will never be flowed away. At that time, I don’t understand the meaning, but now, I start to understand. A tree is tough, it has the strong life and no matter how the weather is like, it still stands on the ground. 
曾经我看到一部电影,里面的男主人公说,他想成为一课树,因为树是稳定的,永远不会移动。当时,我不明白意思,但是现在,我开始明白了。树是很顽强的,它有较强的生命力,不管天气如何,它仍然矗立在地上。