The drill starts when the batsman calls Yes. At this point the batter must run with the bat in hand and try to complete two runs.
However, the batter is racing against the fielders.
Fielder 1 rolls the ball out to the player waiting in line who must then use a two handed pick up before returning the ball over the stumps to the wicket-keeper. After the ball is thrown player 1 joins the back of the queue and player 3 takes their place on the cone.
After this the race can start again, this time repeated on the other side for the fielding team.