how to solve this error? and why there is error?

 A11 = diff(A1,1)
 A12 = diff(A1,2)
 A21 = diff(A2,1)
 A22 = diff(A2,2)
 S2 = diff(S,2)
 X2 = diff(x,2)
Eq1 = X2 == (14.344*A1)- (((3*0.3)+(-1.6)+(21*0.3)))/(((21+0.5))*A12 -(((3*0.5)/(21+3))*A22));
Eq2 = Cl == ((((0.5*0.106)*(21+3))+(((0.42*(0.106^2))+1.5)/0.106))*X2)+(((0.44*((0.42*(0.106^2))+0.42))/2*0.106)*S2)+((0.5*0.106*0.3*(21+3))*A11)+(0.5*3*0.106*0.5*A22);
Eq3 = Cr == ((((0.5*0.106)*(21+3))+(((0.42*(0.106^2))+1.5)/0.106))*X2)-(((0.44*((0.42*(0.106^2))+0.42))/2*0.106)*S2)+((0.5*0.106*0.3*(21+3))*A11)+(0.5*3*0.106*0.5*A22);
Eq4 = S2 == (Cl-((((0.5*1.06)*(21+3))+(((0.42*(1.06^2))+1.5)/1.06))*X2)-((0.5*1.06*0.3*(21+3))*A11)-(0.5*3*1.06*0.5*A22))/(((0.44*((0.42*(1.06^2))+1.5))/2*1.06));
Eq5 = X2 == (-0.552*A2) - (2*0.3*A12) - ((((3*(0.5)^2)+10.66)/(3*0.5))*A22);
Eq6 = A12 == (-56.419*A1)-(((2*0.3*(21+3))/((4*3*(0.3^2))-1.6+(21*(0.3^2))))*X2)-(((2*3*0.3*0.5)/((4*3*(0.3^2))-1.6+(21*(0.3^2))))*A22);
Eq7 = A12 == (0.579*A2)-((1/(2*0.3))*X2)-((((3*(0.5^2))+10.66)/(2*3*0.3*0.5))*A22);   
Eq8 = A22 == (29.262*A1)-(((2*0.3*(21+3))/(2*3*0.3*0.5))*X2)-((((0.3*3*(0.3^2))-1.6+(21*(0.3^2)))/(2*3*0.3*0.5))*A12);
Eq9 = A22 == (6.466*A1)-(((3*0.5)/((3*(0.5^2))+10.66))*X2)-((((0.3*3*(0.3^2))-1.6+(21*(0.3^2)))/(2*3*0.3*0.5))*A12);
Eq10 = S2 == (Cr-((((0.5*1.06)*(21+3))+(((0.42*(1.06^2))+1.5)/1.06))*X2)-((0.5*1.06*0.3*(21+3))*A11)-(0.5*3*1.06*0.5*A22))/-((((2*1.06)/(0.44*((0.42*(1.06^2))+1.5)))));
[VF,Sbs] = odeToVectorField(Eq1,Eq2,Eq3,Eq4,Eq5,Eq5,Eq6,Eq7,Eq8,Eq9,Eq10)
coupled_vanderpol = matlabFunction(VF, 'Vars',{T,Y})
%x0 x. A1 A1. A2 A2. S S.
t0 = [-0.1,0,0,0.03,0,0,0];
tspan = [0,10];
[t,v_z] = ode45(@(T,Y)coupled_vanderpol(T,Y),tspan,t0);
figure
plot(t, v_z)
grid

[Cris LaPierre]

Minor detail - you forget to say what the error is. Please copy/paste the entire error message (all the red text) here.

And you haven't defined A1, so we can't even run the code you shared.