What does film grain count mean?

The so-called graininess is a by-product of poor film photography quality, just like the high ISO noise of digital photos, which photographers try their best to avoid.

Just as digital photos are made up of pixels, film is made up of silver salt particles.

In addition, as a unit, the size of pixels is fixed, but the size of silver salt particles is not the same. Different types of films have different particle sizes. Generally, newer models and more expensive films have finer grains.