What does the squiggly line mean when it starts at zero on a graph?

it means that from zero to the first number next to the graph is not in the same order as the other numbers. for example it might me 0,10,15,20,25. there will be a squiggly line after 0 because 0+5 is not 10 and the pattern here is adding 5 each time. hope this helps:)