‘YHVH’ (יהוה) is a Hebrew Acronym that stands for:
‘He was,’
‘He is,’ and
‘He will be’

As shown here:

HaYa (היה - He was)
HoVeH (הוה - He is)
YeHeH (יהיה - He will be) 

Since YHVH is an acronym, it should be pronounced only as such, letter by letter. In Hebrew it is only pronounced as Yod, Heh, Vav, Heh, after the four letters that constitute the acronym. In English one may pronounce it as Y-H-V-H, also letter by letter. No vowels appear between the consonants.

YHVH means 'the Eternal.'

Where does the Acronym YHVH (יהוה) appear first time in the Bible?

ELoHiM represents the Attribute of Justice.  
YHVH represents the Attribute of Mercy. YHVH (Mercy) entered our world as a (spiritual) Ray of Light, on the Sabbath (seventh day).

Then YHVH EloHiM created Adam in HIS ONENESS (Genesis chapter 2).

Where do we see in the text the Acronym YHVH (יהוה) the first time?
For that, let’s examine again the Sixth Day’s events:

"And ELoHIM said let the Earth bring forth creatures, Cattle, creeping things,
And EloHiM made the animals…cattle…and everything creeping
And EloHiM saw that is was good,
And ELoHiM created Adam in His Image
And ELoHiM blessed them saying be fruitful and multiply
And ELoHim said let us make Adam in our form and our image
And EloHiM said behold, I have given you all the grass
And ELoHiM saw everything that He had done and behold, it was Very Good,
And it was evening, and it was morning,
Yom (Day)
HaShishi. (Sixth) - the6th day was over) Genesis 1:31


VaYechulu (and they ended)  
HaShamyim (the Heavens)
VeHaaretz (and the Earth) and all their hosts,
And ELoHiM finished all the work He had done,
And ELoHiM finished on the Seventh Day His work which He had done,
And He abstained on the Seventh Day from all His work Which He had done."  Genesis 2: 1-2  

First (in red) we see the text that describes the Sixth Day, under the Rule of ELoHiM, who is mentioned 7 times before the end of the Day (out of total 32 times in the Story of the Six Days of Creation.)  

Then (in blue) we see the Sabbath, ruled by YHVH (יהוה). Right at the transition between the Sixth and Seventh Days, we see the Acronym YHVH (יהוה) in its full Glory the first time ever, sitting like a ‘bridge’ over the ‘gap’ that separates the Sixth and the Sabbath Days.


Thus the Acronym YHVH (יהוה) appears the first time in the Torah,
As a beautiful Acronym!

YH (יה) is the Ray of Light that has entered our World.
YH (יה) is the Light that is spread by the Holy Temple Menorah.
YH (יה) is the Light of MERCY we draw from the Eternal Sabbath.
YH (יה) ‘dwells’ in our heart, and is therefore called the Shechinah (from lishkon, to dwell).

Many biblical names end with YaH, like
JeremaYaH (YH shall be exalted)
NetanYaH, (YH has given me)
ChezekeYaH, (YH is strong)
IsaiYah (YH has saved us)
And many more such names. They express YHVH’S presence in our world.