The lyrics mean:
When the sky is dark and concealed alone in the crowd,
No one can save me from this loneliness.
I won't let me drown in this mud,
I open my hands and bravely move forward.
No matter how difficult the road is, no matter how lonely I am.
Look how vast the sky is.
I open my hands and bravely walk forward, after the rain, there will be a rainbow
The Good Friend Mission Clubhouse