This video on the Austrian business cycle seems to state that when rates are low this signlas to investors that there is plenty of money to borrow and plenty of resourses to deploy. However I dont understand to 100% how resources and available cash are linked tho, whats the idea? Why must low rates mean plenty of resourses?
As a disclaimer, I think the Austrian business cycle is incorrect. I will try to explain in a sympathetic fashion. Mises.org has a great deal of resources on Austrian economics, much of it free.
From a quick watch of the beginning of the video, the distinction is between a market rate of interest, and the “artificial” interest rate set by the central bank.
In the case of a market rate of interest, the belief is that prices for everything will set to some balanced arrangement: the demand for investment goods will balance the supply, and there will be a matching balance in lending activity (with the interest rate on loans being the price that clears the market). In classical economics, this balance would be described as an equilibrium. However, different Austrians disagree on how to describe this, but they generally reject using “equilibrium.” You would need to find another source to explain their terminology.
Getting to your question, Classical authors can explain why the balance in lending markets coincides with the balance in physical resource markets in equilibrium. Roughly speaking, if any market is unbalanced, this would unbalance other markets, so all of them have to end up in equilibrium. The Austrians somehow end up with the same conclusion, but different authors appear to explain it differently.
(The issue with “artificial” interest rates is that Austrians argue that central banks invariably set interest rates too low, and thus there is excessive investment - “mal-investment.”)
I too also think the austrian theory of the business cycle is incorrect but will offer a sympathetic answer. It really about understanding how the theory related to the structure of production and how lower interest rates incentives activities that are further behind in this structure and extends the time for this process to occur.
Its interpreted as a signal for entrepreneurs to invest their time in production that is further from the market than that which is closer.