Substring Counting

[krisputas]

x = 0
for s,_ in enumerate(haystack):
    haysub = haystack[s:len(needle) + s]
    if haysub == needle:
        x += 1

print(x)

I seem to be not understanding something with how the loops work. Could you please elaborate in a simple manner why in line 4 you've used the +s part?

Thank you