asks: How do you make a good fight scene so readers can understand clearly of what's happening?

Three vital things keep your fight scenes interesting and fun.

A major mistake is to write too much description. You may think you're describing the action in awesome detail, but too much detail slows everything down. Here's an example:

The man jumped out of the bushes, brandishing a hunting knife with a serrated edge in his right hand. Jane's instincts kicked in, and she whirled around, kicking her left foot out, and knocking the knife out of his grasp.

Some of the details we can do without, unless they are relevant to the plot. Nobody cares which hand he's holding the knife with, nor do we care which foot she kicked with. We don't even need to know the knife was serrated unless it's a clue to something else. Actually, even then, the knife's serrated edge should be mentioned after the fight, when looking for clues. Here's an abbreviated version of this scene:

The man jumped out of the bushes, pointing a knife at her. Jane whirled around, all instinct, and kicked the knife out of his grasp.

We've said the same thing with fewer words, and now we can get on with the next piece of action. Quick pacing is crucial to a good fight scene. Never bog down a reader with too much description.

Don't insert a pointless fight. Action scenes should move the plot forward. There needs to be a reason for the fight, or else the reader is going to think, "Why is this here?" The reason could be to reveal personality, introduce characters, resolve a conflict, or numerous other purposes. So long as the reader gleans information from this fight, it serves a purpose.

Don't follow the same action sequence more than once. Even deja-vu scenes should be handled differently so it doesn't feel like we're reading the same thing over again. By keeping each fight fresh and different, the reader won't lose interest.

To get back to the original question, which is making the reader understand clearly what's going on, I have this to say: Don't underestimate the reader's imagination. Given a few key details, the human brain has an incredible aptitude for filling in the blanks. The important thing to remember is the reader needs to understand the plot, not the exact way a fight happened in the writer's imagination. It's a bit arrogant to want readers to imagine things exactly as you did. No two people experience the same thing alike. Ask any crime scene investigator. The point of your writing is to entertain, so if you imagined Jane kicking with her left foot while the reader imagined the right, does it matter? Not at all. So don't worry about trying to transplant a scene exactly from your brain to someone else's. Just make sure the key details are there to support the forward movement of your story.