“Everything that is reasonable is realistic, and everything that is realistic is reasonable.”
Reality and existence are different. The word "reality" in German means "realization". What exists is not necessarily reality.
Hegel is an objective idealist. He believes that the development of all things is moving in a rational direction. At the same time, dialectical thinking is also the reasonable core of Hegel's philosophical thought. Only when something is reasonable can it become reality. And if a thing is realistic (it is realizing itself), it means that it is reasonable.
We need to use the perspective of dialectical negation to analyze, understand and grasp reality and existence. They have reasons and basis for their actual existence. But at the same time, there are also reasons to deny itself and lead to its demise.
What is reasonable and in line with the laws and inevitable processes of the development of things may not be a reality yet, but it will eventually become a reality.