Can someone help me get a better understanding of StackInterface in java?

I also am having trouble with some of these methods i need to write.

public interface StackInterface {

/**

* Add element to top of stack.

* @param newEntry item to add to stack.

*/

public void push(T newEntry);

/**

* Remove and return top element from stack.

* @return top element.

* @throws EmptyStackException if the stack is empty

*/

public T pop();

/**

* Return top element from stack without modifying stack.

* @return Element on top of stack.

* @throws EmptyStackException if the stack is empty

*/

public T peek();

/**

* Whether stack is empty.

* @return True if stack is empty, false otherwise.

*/

public boolean isEmpty();

/**

* Remove all elements from stack.

*/

public void clear();

}