When you talk about fiber, you could say there are two big groups, the soluble ones, and the insoluble ones.
The soluble one is good because together with water helps to eliminate cholesterol and fatty acids, bad for our body if there's too many, also, it helps to control blood sugar levels.
The insoluble one is good because it keeps you satisfied, helps to accelerate intestinal transit that allows preventing constipation and with that some diseases like irritable bowel syndrome, and hemorrhoids.