The B vitamin complex is varied and certainly important. One of the many B vitamins is pantothenic acid (vitamin B5), an important part of Coenzyme A (CoA). CoA is known for its acetylation properties–most proteins with added acetate groups were modified by CoA, and this modification changes shape of the proteins (and thus the function). This is especially important for the replication of DNA .
Histones are positively charged proteins that our negatively charged DNA coils around. However, when these proteins are acetylated, they lose their positive charge, and the DNA coils less tightly. This relaxes the DNA and is associated with increased gene expression (Plain English Translation: we make more proteins for genes that come from relaxed DNA) [2, 3]. This can have huge repercussions for our bodies–it can change whether we produce the right amount of inflammatory proteins or antibodies, for instance.
Coenzyme A is also known for its role in metabolizing the macronutrients and their building blocks: fats, cholesterol, and fatty acids; proteins and amino acids; and carbohydrates. Even things like heme (as in hemoglobin, as in super important to red blood cells) require CoA, and thus vitamin B5, to produce them .
On a cosmetic level, vitamin B5 is an important ingredient for healthy skin by improving barrier function [4, 5] and healthy hair  by sealing the shaft (similar to how it improves skin’s barrier function).