Although God is one (Deuteronomy 6:4), “us” indicates plurality within the Godhead. “It is…the plural of fullness, which is found in the regular word for God (’ĕlōhîm) used with a singular verb; and this fullness, glimpsed in the Old Testament, was to be unfolded as triunity, in the further ‘we’ and ‘our’ of John 14:23 (with 14:17).”1
26 Then God said, “Let us make man in our image, after our likeness. And let them have dominion over the fish of the sea and over the birds of the heavens and over the livestock and over all the earth and over every creeping thing that creeps on the earth.”