This is the 9940th most frequent Turkish word.
açıklayın
"Explain."
Here, 'açıklayın' is used as a polite command directed at someone, asking them to explain something in greater detail.
Lütfen bu kavramı daha ayrıntılı bir şekilde açıklayın.
Please explain this concept in more detail.
In this context, 'açıklayacağız' is the future tense form of 'açıklamak', showing that the explanation of the topic will be performed by 'we'.
Bugünkü dersimizde bu konuyu açıklayacağız.
In today's lesson, we will explain this topic.
Here, 'açıklıyor' is the present tense form used to describe that the book is performing the act of explaining scientific theories.