(Is not He Who guides you in the darkness of the land and the sea,) meaning, by means of what He has created of heavenly and earthly signposts. This is like the Ayah,
(And landmarks and by the stars, they guide themselves.) (16:16)
(It is He Who has set the stars for you, so that you may guide your course with their help through the darkness of the land and the sea...) (6:97)
(and Who sends the winds as heralds of glad tidings, going before His mercy) meaning, ahead of the clouds which bring rain, by means of which Allah shows His mercy to His servants who are suffering drought and despair.
(Is there any god with Allah Exalted be Allah above all that they associate as partners!)