What does it mean to add four or five orioles without reducing the shade?

Green plants keep coming, adding four or five orioles, indicating that the ancient trees on the mountain road are green and dripping, which is not inferior to the scenery on the water road. A few chirps of orioles came from the depths of the dense forest, which added a bit of interest. From the song dynasty once upon a time, the "three roads in the middle". The original text is as follows

Plum yellow, sunny,

The stream dried up, but it flowed in the mountains.

Shade will not reduce roads,

Add oriole four or five times.