Hi subha.
That is because the animation is looping back to the start. It is playing the frame range you told it to play.
If you scrub past the end of the frame range you will see him continuing to move forward.
You should check out the Fundamentals of Animation first. This course is quick and it will save us both some time because I have a feeling you won’t need to ask as many questions and you’ll be able to move forward faster.
https://cgcookie.com/course/fundamentals-of-animation-in-blender-2-8x
