This entry in a monster description describes how much wealth a creature owns. (See pages 52-56 of the Dungeon Master's Guide for details about treasure, particularly Tables 3-5, through 3-8.) In most cases, a creature keeps valuables in its home or lair and has no treasure with it when it travels. Intelligent creatures that own useful, portable treasure (such as magic items) tend to carry and use these, leaving bulky items at home.
Treasure can include coins, goods, and items. Creatures can have varying amounts of each, as follows.
Standard: Refer to Table 3-5 in the Dungeon Master's Guide and roll d% once for each type of treasure (Coins, Goods, Items) on the Level section of the table that corresponds to the creature's Challenge Rating (for groups of creatures, use the Encounter Level for the encounter instead).
Some creatures have double, triple, or even quadruple standard treasure; in these cases, roll for each type of treasure two, three, or four times.
None: The creature collects no treasure of its own.
Nonstandard: Some creatures have quirks or habits that affect the types of treasure they collect. These creatures use the same treasure tables, but with special adjustments.
Fractional Coins: Roll on the Coins column in the section corresponding to the creature's Challenge Rating, but divide the result as indicated.
% Goods or Items: The creature has goods or items only some of the time. Before checking for goods or items, roll d% against the given percentage. On a success, make a normal roll on the appropriate Goods or Items column (which may still result in no goods or items).
Double Goods or Items: Roll twice on the appropriate Goods or Items column.
Parenthetical Notes: Some entries for goods or items include notes that limit the types of treasure a creature collects.
When a note includes the word "no," it means the creature does not collect or cannot keep that thing. If a random roll generates such a result, treat the result as "none" instead. For example, if a creature's "items" entry reads "no flammables," and a random roll generates a scroll, the creature instead has no item at all (the scroll burned up, or the creature left it behind).
When a note includes the word "only," the creature goes out of its way to collect treasure of the indicated type. If an entry for goods indicates "gems only," roll on the appropriate Goods column and treat any "art" result as "gems" instead.
It's sometimes necessary to reroll until the right sort of item appears. For example, if a creature's items entry reads "nonflammables only," roll normally on the appropriate Items column. If you get a flammable item, reroll on the same portion of the table until you get a nonflammable one. If the table you rolled on contains only flammable items, back up a step and reroll until you get to a table that can give you an appropriate item.