class - C++ : Understanding implicit typecasting for classes with a constructor with 1 argument

Would appreciate clarification on what exactly is happening when a constructor has only one argument and it is said that it does an implicit cast to the class type - right there It is confusing to me because :

class dog {
public :

        dog(string name) {    mname = name;}
private :
         string mname;
};

I don't understand how a type string can be converted to a type dog, I can see how it can be passed in and SET another string but if a string is converted to type dog what would that even mean? Would it be type dog that gets assigned a bit wise copy of a string?