The word Mvest is an abbreviation which simply means million vest. This is to say a million vests makes up 1 Mvest. Mvest is a measurement unit of steem power on steem blockchain.
As at the time of this post 1 steem power = 1, 758.704676 vest.

You have successfully explain the abbreviation of Mvest and its really true that these are 1 million VEST and I agree with you that there is a measurement unit at the blockchain and that measurement unit for measuring the power of a person is called Mvest and this is a measurement unit for measuring the power thats why it also plays a very important role in influence of a person at the blockchain as well as in the worth of vote a user have at the blockchain.

if the user does not have steem to powerup then there will be no steempower and no vest.

Power up is the process where steem is converted to steem power. No steem > no power ups > no vest

I agree with all the things that you have explained while explaining the relationship between Power and Mvest but the most important and interesting part of your elaboration in the relationship is a formula or you can say and expression that you made that if we don't have tokens then we cannot convert these tokens into our power and then ultimately there will be no Mvest so I want to add in this expression that if all these things will be absent then there will be no influence of a user at the blockchain

I wish you good luck In this engagement challenge and hopefully next time you would be again with another interesting important and informative participation as you did this time so good luck to you.