It restricts the menu for subscribers of that group. Pick one or more meal categories; the selection is copied onto every subscription created in the group and, when the customer (or auto-select) chooses meals for a delivery, only meals that match the group's categories are offered — evaluated per category group using the Category Union rule. Leave it empty to offer the full menu. The admin groups list shows the chosen categories as coloured letter-tag chips.

This is different from the per-price Customize meal categories for this plan setting, which fixes how many meals of each category are included per day.