Here’s what the code from Turtle Challenge #392 draws. This picture was made by running the code for real.

The answers
How many circles will the turtle draw? 18 circles, one each time round the loop.
Why does the turtle turn 20 degrees after each circle? Because 18 × 20 = 360, so the circles spread evenly all the way round, like petals on a flower.
What colour is the flower? All forestgreen.
How the code works
t.circle(80) draws a whole circle and brings the turtle back to the same spot. Turning a little between circles makes a flower pattern.
import turtle
t = turtle.Turtle()
t.speed(0)
t.pensize(2)
t.pencolor("forestgreen")
for petal in range(18):
t.circle(80)
t.left(20)
t.hideturtle()
turtle.done()
Try it: What happens if you use t.circle(80, 180) instead? (That draws half a circle.)