This apple is a countable noun.

This plan is unrealistic.

Since it started raining, I opened my umbrella.

He was a very excellent student before he turned to delinquency.

He is receiving countless blessings.

'Apple' is a count noun, and you can count it as one, two, etc.

He was called an unpatriotic person because of his actions.

The war crime was condemned as inhumane by the international community.

The problem of illiteracy is a serious social issue around the world.

She publicly acknowledged that she is asexual.