When a foraging bee collects nectar and pollen from the flower of a plant, some pollen sticks to the hairs of her body. As she visits other flowers, pollen is transferred to other flowers, allowing for pollination. When the flower is pollinated, fertilisation can occur and fruits with seeds develops, allowing for plant proliferation. The pollination process is shown below.

 

Pollination process. Source: Encyclopaedia Britannica.

Bee covered in pollen. Source: Bee Informed! wordpress, https://beependent.wordpress.com/pollination/

Many of the fruits, veggies, nuts and other plant based products are pollinated by bees. In fact, almond trees are amongst one of the many plants that are solely pollinated by bees. More information can be seen from the picture below!

Plants pollinated by Bees. Source: Fix, https://www.fix.com/blog/creating-a-bee-friendly-garden/

Larger and more uniform fruit is produced by flowers that are visited more often by bees. This is the most apparent in fruits born by trees.

Therefore, without bees, plants would not be able to reproduce, or would not be able to produce proper fruit. This includes many fruits, vegetables and food crops.