Many readers of the Bible have noted that the Hebrew word for God, Elohim, is plural given the -im ending and wondered how that squares with strict monotheism. Some, usually with a Christian agenda, have anachronistically read Trinitarianism into it. Some, usually with an counter-Christian agenda, have provocatively read polytheism into it. I would like to suggest both are mistaken.
Elohim is a plural word, but it functions as a plural or a singular word depending on the context. This is not as strange as it sounds. Consider the words: sheep, fish, squid, scissors and aircraft. They're all words for which the plural and singular forms are the same.
Now let's read Genesis 1:26-28, the source of this controversy, with this in mind.
Then Elohim said, “Let us make humankind in our image, according to our likeness ... So Elohim created humankind in his image, in the image of Elohim he created them; male and female he created them.
I would suggest that what we have here is a single person, God, addressing a group, the heavenly hosts or divine assembly, what these days we call angels. Then having made the announcement God goes ahead and acts - unilaterally. The others watch, just as they did when God laid the foundations of the earth (Job 38:4-7). Maybe that's why Daniel calls them Watchers (Daniel 4:13,17).