Answer 1

because, when you run the code on a ide. the string is shown as a prompt in the terminal.
here's what you see
enter a number: waits for a number to be given.
enter a number:5 gets a number
program ended

Answer 2

Timo Luege you have a input as
input ("enter a number")

if you don't want to show the phrase "enter a number", simply have:
x =int (input())
if x > 5:
print(x," is greater than 5")
print("Program ended")