“יהי אור” “Let there be Light” is a light that came out from the first ‘אויר’ ‘air’ and is a secret of ‘אל’ that is a name representing the Light of the Endless on the right column, Chessed.
“ויהי” “and there was… (Light)” represents the Left, darkness, Gevurah and the name “אלהים”.
The Light “אור” and the letter י Yod that came from Keter joined together and form the state of “אויר”, “Air”.
“וַיַּרְא אֱלֹהִים אֶת הָאוֹר כִּי טוֹב” “And God saw that the light is good” is the central line that connected the Right, Chessed, and the Left, Gevurah. Because they joined together as Tiferet, the Left that was dark before is now with Light.
After this unification the Light was separated again and formed below Tiferet, the Sefirot of Netzach on the Right and Hod on the left.
(Genesis 1:5) “וַיִּקְרָא אֱלֹהִים לָאוֹר יוֹם וְלַחֹשֶׁךְ קָרָא לָיְלָה” “And God called the light “day,” and the darkness He called “night.”. ‘And God called’ is the process of drawing Light from the Right side of Chessed of the Center column, Tiferet, to form the Sefira of Yessod that is called “Day”.
From the Left side, that is darkness came the “Night” that is the Sefira of Malchut that doesn’t have the light of its own.
The air ‘אויר’ we breathe has the Light ‘אור’ of the ‘י’, ten Sefirot in it. Without air, there’s no life.
The last few Zohar paragraphs describe in general the formation of the seven Sefirot and the seven days. The Sefirot formed in a process that was started from the Light of the Endless. The first appearance of Light has in it all the lower levels below it.
The first day of Chessed included the entire week. The Torah describes the first day of Creation as “יום אחד” “Day One”, not as the ‘First day’ as the Torah describes the rest of the days, “Second day”, “Third day”, etc. That tells us that the first day had the entire week in it.