While Guardians can neither view nor download your documents, they do control access to that information. So, in emergency situations, Guardians act as your proxy for determining if access should or should not be granted to your Vaults.
Choose only those people you thoroughly trust to act as Guardians for your vaults, such as a close friend, an attorney, trusted business associate, or your financial advisor.
Fidelius recommends at least two Guardians on each Vault for redundancy (what if one person can’t be reached?), but you can choose as many as you feel you need.