Genesis 1:1-3 says:
My transliteration (I don't follow the normal convention, but aim more at accuracy an pronunciation, the word "Eloheem" it typically spelled "Elohim") :בְּרֵאשִׁית בָּרָא אֱלֹהִים אֵת הַשָּׁמַיִם וְאֵת הָאָרֶץ וְהָאָרֶץ הָיְתָה תֹהוּ וָבֹהוּ וְחֹשֶׁךְ עַל-פְּנֵי תְהוֹם וְרוּחַ אֱלֹהִים מְרַחֶפֶת עַל-פְּנֵי הַמָּיִם. וַיֹּאמֶר אֱלֹהִים יְהִי אוֹר וַיְהִי-אוֹר
B'résheet bara Eloheem ét hashshamayeem v'ét ha'aretz hay'tah tohu va'vo'hu v'ḥosheḥ al-p'néy t'hom v'ruaḥ Eloheem m'raḥefet al-p'néy hammayeem. Vayyomer Eloheem y'hee or vay'hee or.One of the translations of it is:
In the beginning God created the heaven and the earth. Now the earth was unformed and void, and darkness was upon the face of the deep; and the spirit of God hovered over the face of the waters. And God said: 'Let there be light.' And there was light.
The words in read are the words that have the plural ending in Genesis 1, they are "God-Eloheem," "hashshamayeem-heaven", "hammayeem-water." Most people don't know the words water and heaven in Hebrew have plural endings, in fact does the word face. Anyway, let's focus on the phrase וַיֹּאמֶר אֱלֹהִים יְהִי אוֹר וַיְהִי-אוֹר which means "(and) God said "there shall be light", and there was light." The word for said here is singular וַיֹּאמֶר its used for when there is one person speaking, not more than one, it shows the plural ending ים of the word אֱלֹהִים Eloheem does not refer to the third person plural (that is "they"), but rather the third person singular (that is "he). Let's compare a verse where multiple people say something with this (the word for speak is highlighted):
Genesis 11:4 says:
וַיֹּאמְרוּ הָבָה נִבְנֶה-לָּנוּ עִיר, וּמִגְדָּל וְרֹאשׁוֹ בַשָּׁמַיִם, וְנַעֲשֶׂה-לָּנוּ, שֵׁם
And they said: 'Come, let us build us a city, and a tower, with its top in heaven, and let us make us a name;
Genesis 1:3 said:
וַיֹּאמֶר אֱלֹהִים יְהִי אוֹר וַיְהִי-אוֹר
And God said: 'Let there be light.' And there was light.
The word in in Genesis 11:4 וַיֹּאמְרוּ vayyom'ru is the third person PLURAL, which means 2 or more are speaking, however, Genesis 1:3 uses וַיֹּאמֶר vayyomer, which means just one person is speaking! If "Gods" were intended in Genesis 1:3 it would've read:
...וַיֹּאמְרוּ אֱלֹהִים יְהִי אוֹר
In this case it would be translated:
"And gods said: "Let there be light!"..."
(Note, I leave the rest of the verse out, so as not to tarnish the sacred text with corruption.)