The problem is referring to the distance along the diagonal that connects the home plate to second base. So 14m from the home plate along this diagonal is the pitcher's mound.
A little league baseball diamond has 4 bases forming a square whose sides measure 20m each. The pitcher mound is 14 m from the home plate on a line joining home plate and second base. Find the distance from the pitcher's mound to 3rd base.
I don't get the bolded part of the problem. Can anyone explain to me, or show it in a diagram. Does it mean that the distance from pithcer's mound and2nd base is 14m in distance?
Not quite. The original statement says the pitcher's mound is 14m from home plate. It doesn't say anything about how far the pitcher's mound is from second base - I wouldn't assume that it is also 14m. If it were, you'd have a right triangle with sides 20, 20, and 28 (14 + 14), but 20^2 + 20^2 does not equal 28^2, so it can't be a right triangle.