The song is about Radha and Krishna. In this song, Krishna has become an emperor, which is far removed from the simplicity of his earlier life that he spent in Gokul. In Gokul, he was a cowherd with no material possessions besides a flute that he loved to play. Yet, he was happy and content. Today, as a king, Krishna has wealth, power, and every worldly pleasure a man can ask for, but he is not happy. In his heart, he yearns for the simple life in Gokul. Above everything, he cannot forget Radha, the love of his life. Radha loved Krishna unconditionally when he was another village boy. Today many attractive women desire Krishna the emperor, yet the purity of Radha's love is what his heart longs for. So, Krishna wishes to leave the capital of his kingdom Mathura to return to Gokul and meet Radha, one last time.
To my mind, this song is from the viewpoint of Krishna, where he is examining his own inner state in a detached manner.
Here is a translation of the song in English that I found on the web, followed by a beautiful rendition by Madhubanti Bagchi.
What struck you suddenly this morning?
Why do you want to return to Gokul,
Your fine garments leaving
The golden crown lowering
On the ground the scepter flinging
Why pick up the flute to play?
What magical song did the birds at Gokul sing?
That makes you give up your kingdom like dust
And, your heart, in longing sighs,
is no longer in kingly matters!
Your subjects watch with worried eyes:
Your bed of roses seem thorns to you,
You stay awake the whole night, restless.
You call the chariot at midnight, why?
Slowly you would reach the shores of the river
Lonely waters where breezes quiver
You would feel the bittersweet pangs
And you would think about Radha, of course!
Your first love is another man's wife today
Household chores are hers alone
She wiped away the tears of separation long back
Why fill her with fresh dismay?
Why, then, do you want to return to Gokul,