Here is a basic explanation of pollen and some photos of how it is stored in the hive.
Honeybees collect pollen from flowers. Some of it is transferred to other flowers, fertilizing the flower so a plant can produce fruit. (Pollen is essentially the "sperm" to fertilize the flower "egg.")
Worker bees bring pollen back to the hive and store it in honeycomb cells. Later, nurse bees will feed pollen to brood. Spring pollen stimulates the queen to lay eggs to build up the colony after winter.
Pollen is made up of amino acids, which are consumed by larvae to build the protein in their bodies. It is sometimes called "bee bread" because it has a bread-like texture when stored in the comb.
Pollen is bee protein. Honey is bee carbohydrates.
In the newly installed package below, bees have drawn some comb and filled some of the cells with multi-colored pollen. The pollen color is different for each plant bees visit. Bees do best when there is a variety of different pollen sources.
Pollen from several plants can be stored in one cell.
Bees sometimes store nectar within the same cell as pollen. (The shiny liquid below is nectar, which needs to be cured to make honey.) Having pollen below honey in cells can make it tricky to estimate how much pollen is in the hive. We really can't see it when honey cells are capped over.
One more thing: Some people like to consume pollen, or honey with pollen particles inside, to help with their seasonal allergies. It seems to help them. It is important to get pollen or honey produced in the season to match allergy inflammation.