I was one of the "business guys" at DigitalOcean from very tiny to big. Execution looked like: 20% of the time in meetings discussing what the next period of time without seeing each other was going to look like and 80% of the time on flights and in hotels. My mantra was always "be directionally correct, go to market as hard as I can every single day, and fully trust the engineers building the products around me".
If your "business cofounders" aren't closing deals and landing sales they're useless. So if you're going to join a "non-technical founder" they must both have the contacts or a in in the industry you'll be trying to join and must be a great salesman.
If they don't have that, walk away, this person has no value.
The ability to execute means to deliver timely and on budget.
I have seen people who would not be able to set up and manage a hot dog stand and yet they were trying to run a business with 50 employees. The only result was burning money like there was no tomorrow.
How do we define what execution looks like?
As a general rule we must be wary of “business cofounders” who sell pontification as execution.