A leader is a person who can lead members in thean organization to achieve a common goal.

or "members of an organization"

Therefore, we can say that a leader plays a very important role in deciding the success as well theor failure of the organization.

this flows better

I assume that the conditions forneeded qualities of a leader are leadership skills and promotion skills.

I don't know what you mean by promotion skills. Based on what you say later, technical skills?

First, leadership skills include those abilities that guide and encourage a group of people toward achieving a set of goals.

They also need to decide the suitable positions for each person and encourage them to play that role well.

or "encourage them to perform well in that role".

Second, promotiontechnical skills include strengths that to push work effectivecontribute significantly toward the goals.

or do you mean planning skills?

As a result, a leader when leading work needs to have outstanding abilities and clear direction.

or "when delegating work", "when managing their workload"

A true leader really needs to be aware of their own judgments in leading the organization.

I'm not sure what you mean by judgements. They need to be aware of their own biases?

Therefore, they should be able to have empathy and communication skills when receiving opinions ofrom other members/employees and then give a direinstructions.

Finally, I have summarized the roles, conditionsneeded qualities, and points to keep in mind of a leader.

I think I'd say "duties" instead of "roles"

In order to be a good leader, they need to have leadership skills, pushingand the ability to push/guide and leading the organization,. They need to respect the opinions and characteristics of the organization’s members, as wellnd make the effort to empathize and communicate.

This is how I would write this. Your list is slightly muddled as you mix nouns they should have as well as verbs they should do. I think splitting them makes it flow better.

A leader is a person who can lead members in thean organization to achieve a common goal.

An would fit better than article 'the' because you have just introduced the noun 'organization'

So, what defines a true leader?

comma after the word SO acts like a pause.

First, leadership skills include abilities that guide and encourage a group of people toward achieving a set of goals.

Second, promotion skills include strengths that to push work effectively toward theeffectively drive work toward achieving goals.

Incorrect use of "to" in "strengths that to push" it disrupts the sentence flow.
push work effectively toward the goals - this is vague and the reader is not able to understand the writer.

As a result, a leader when lead work need to haveneeds outstanding abilities and a clear direction when leading work.

I have just rearranged the statement to make it grammatically palatable

A true leader really need to be aware of their own judgments in leading the organization.

Therefore, they should be able to have empathy and good communication skills when receiving opinions of other members and then give a direction.

Finally, I have summarized the roles, conditions and points to keep in mind of, for a leader.