Which in his times he shall show - Which God will reveal at such times as he shall deem best. It is implied here that the time is unknown to people; see the notes on Acts 1:7.
Who is the blessed and only Potentate - God, who is the ruler over all. The word used here - δυνάστης dunastēs - means one who is “mighty” Luke 1:22, then a prince or ruler; compare Acts 8:27. It is applied here to God as the mighty ruler over the universe.
The King of kings - Who claims dominion over all the kings of the earth. In Revelation 7:14, the same appellation is applied to the Lord Jesus, ascribing to him universal dominion.
Lord of lords - The idea here is, that all the sovereigns of the earth are under his sway; that none of them can prevent the accomplishment of his purposes; and that he can direct the winding up of human affairs when he pleases.