Answer 1

x,y,z = 0,1,0
This is defining these variables in order, with x being 0, y being 1, and z being 0.

i = 1000
This is setting the i variable to 1000.

while y<i:
Everything after the colon is going to run as long as y is less than i.

z=x+y
z is equal to the sum of x+y

x=y
Setting x equal to y

y=z
Setting y equal to z (which will eventually break the loop)

print (y)
Prints the value of y

Hope this helps. If I made a mistake or if something's unclear, please let me know.