There is a dog gene called Cu locus (AKA Curly Coat Gene) which determines if your dog will have curly hair. The absence of Cu locus means that you will have a straight hair Goldendoodle.
How does a Goldendoodle get a straight coat?
In general, F stands filial and means that it is a hybrid dog, the # means the generation of dog, and the B means back cross.
Which generation of Goldendoodle has a Straight Coat?