The USAA Rewards Visa Signature Card categories for bonus rewards are gas and dining. Purchases that fall into the USAA Rewards Visa bonus categories get cardholders extra rewards compared to the card's base earning rate.
Whether a purchase falls into a card's bonus categories depends on “Merchant Category Codes,” which are assigned by the major credit card networks to merchants based on what kind of business they conduct. So if a merchant has the MCC for “gas,” for example, purchases made at that merchant will earn bonus rewards on cards that include “gas” as a bonus category.
When choosing a rewards credit card, it's a good idea to pick a card that offers the opportunity to earn bonus rewards in your most frequent purchase categories. So if you spend a lot in the categories offered on the USAA Rewards Visa, it may be a good card for you.