What does 24k gold clad proof mean?

Clad means coated in jewelry, so a 24 carat clad proof item is plated in 24 carat gold. A proof coin is a coin that is made to create a three dimensional effect, with a raised picture on a smooth mirror-like background. Proof coins are usually struck twice or more in their creation to create their unique look. Generally proof coins do not have monetary value, they just have collector value.