One serving against a day's fiber
The Dietary Reference Intakes set an Adequate Intake for total fiber of 25 g a day for women aged 19 to 50 and 38 g for men of the same ages. Measured against those, the 5.6 g in a 1 cup serving of pecans, unsalted is 22% of the first and 15% of the second. US food labels use a single Daily Value of 28 g instead, which puts this serving at 20%.
Calorie for calorie, the figure is 0.7 g of fiber per 100 kcal (this serving is 754 kcal). Among the 34 nuts with USDA energy data here that is 23rd, and 826th across all 957. The intakes above were derived from 14 g of fiber per 1,000 kcal, or 1.4 g per 100 kcal, so this food sits below the ratio a whole day of eating is meant to reach.
Getting all 25 g from pecans, unsalted alone would take 5 servings, and 38 g would take 7. Most days reach the target through several different sources.
Soluble vs Insoluble Fiber: What Each One Actually Does · All fiber guides