Linguistically speaking, what, if any, connection might there be between the sounds of certain words and their meanings?

How has language evolved?

How does certain sounds turn into certain meanings?

PLEASE provide the answer in "layman's term", since this question was asked to me by a friend of mine & he'd expect me to be able to articulate my answer thoroughly WITHOUT any confusion.

There is no known answer to that question which can be stated simply and thoroughly and without confusion.
If you are interested in researching it for yourself, you might start with something by Pinker.  I don't recall where I saw it, but he reports somewhere on the hypothesis that a mapping of whole body motions onto analogous tongue motions somewhere in the brain may have been the origin of a sound-to-action connection.  Your body moves a certain way, raising the arms, let's say.  This creates a certain pattern of electric impulses in the neurons related to the arms.  Now if the tongue is moved so as to create a similar or analagous pattern of impulses in the neurons related to the tongue, so that the tongue is (from the viewpoint of neural activity) "doing the same thing as the body does" when it raises the arms, then the tongue will automatically shape the sounds that mean "raise arms".

Now all you do is add about a thousand more steps to explain how this could be and collect millions of pieces of data in support of the hypothesis, and you have the explanation you're looking for! 

CJ