Here is Buttercup demonstrating the pincer grasp:
When starting baby-led solids it is recommended to offer your baby "french fry-shaped" foods. That's because anything smaller than that: a) is nearly impossible for a baby to successfully pick up and put in their mouths, b) could pose a choking hazard. Once your baby has developed a pincer grasp, however, a whole new world opens up to them. When babies fingers can pincer small items it's a sign that their mouths have also matured to the point where smaller foods become safe. You obviously want to still avoid hard, round items (candy, nuts, hot dogs, whole grapes, etc).