山花紅紫樹高低。on the colorful flowers among different branches.

始知鎖向金籠聽， Even locked in the cages of gold,

不及林間自在啼。 They wont sing mellifluously as in woods.

PS. Attached is the version of DeepSeek:

Hundreds of trills freely drift with wings in flight,
Amidst red-purple blooms on branches high and low.
Now I know - when caged in gilded bars so bright,
Their song wont flow as wild in woods we know.