To have some knowledge is to be prepared, and that is very good for any circumstance that may occur.

I don't know about mechanics but I know how to change a water, gas or electricity pipe. I have done it. Mechanics often rip people off because people don't know about these things.... masons too, but I am prepared and I know how to do the job, to give an example.

It's important to know a bit about everything and to be prepared.