The LORD reigns, he is robed in majesty; the LORD is robed in majesty and armed with strength; indeed, the world is established, firm and secure. Psalms 93:1(NIV)
While there are human authorities and powers the Lord is the supreme head of all dominion and might. The Lord reigns not only in heaven but also over the earth. He rules not only in the spirit realm but also in the physical.
In verse 5 we get the full understanding of “the Lord reigns”. Psalms 93:5 (NIV) Your statutes, LORD, stand firm; holiness adorns your house for endless days.
His statutes are His royal decrees or instructions or directives.
So the Lord reigns means what He says or commands goes. The Lord has the say so. He has the ultimate say in all the affairs of men.
Therefore in whatever we intend to do we ought to seek to find out what the Lord the supreme ruler of the universe has to say.