how does subbplot work in matlab code example

Example: clf subplot matlab

h1 = subplot(2,1,1);
hold on
x1=(0:0.01:10);
y1=sin(x1);
p1=plot(x1,y1);
h2 = subplot(2,1,2)
hold on
x1=(0:0.01:10);
y2=sin(x1)+cos(x1);
p2=plot(x1,y2,'Color','r');
cla(h2)
cla(h1)