This site names Vitamin B12 specifically for two roles — nervous-system function and brain energy — worth understanding on its own, separate from the other five ingredients.
Vitamin B12 is described as an essential vitamin that supports healthy nervous-system function, brain energy and everyday mental performance, positioned as the formula's energy-and-function-focused nutrient.
Unlike the five other ingredients, which cite PubMed or NCCIH research links, B12 is cited from the NIH Office of Dietary Supplements fact sheet — worth checking that specific source if B12's role interests you.