Q.My Apple Tree Isn’t Bearing Fruit This Year.
I have an apple tree(approximately 5years old) which is not giving fruit this year. In previous years it has had lots of apples on it.

Certified GKH Gardening Expert
This sounds like a deficiency in phosphorus and potassium! Take a soil sample and test the nutrient content and pH to know, exactly, how much you need to add.
Should a soil test show that you nutrients and pH are within range, then you can chalk it up to environmental issues.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/edible/fruits/apples/no-fruit-on-apple-trees.htm
https://www.gardeningknowhow.com/edible/fruits/apples/apple-tree-feeding.htm