What is a solo 401k and why should i have one if I'm starting out

[Joe Khan]

My wife and I would like some information about a solo 401k 

We have decided to invest in real estate and would like to invest under a LLC.

I read a few post about solo 401k but I'm unsure of the benefits. 

My questions are :

Why should i open a solo 401k ?

Who can I go to so i can open a solo 401?

How do investors use the solo 401k for their benefits ?

Thank you BP community for any help offered.