Help ---> matrices X and Y must have the same size as Z

x = 0.01:0.01:2;
y = 0.01:0.01:2;
z = 0.01:0.01:2;

rex = reshape(x,10,20)
rey = reshape(y,10,20)
rez = reshape(z,10,20)
% Variable 'x' denotes the draw current of the device. It is also
% the current that is running through the wire. Measured in Amps (A).
% Value --> 0.01 Amp to 2 Amp with an interval of 0.01 Amp 

% Variable 'y' is the time in seconds (s). This variable is used to
% characterize the AC current graph that is a sine wave.
% Value --> 0.01 s to 2 s with an interval of 0.01 s 

% Variabe 'z' is the distance from the current carrying conductor
% measured in centimeters (cm).
% Value --> 0.01 m to 2 cm with an interval of 0.01 m 


[X,Y,Z] = meshgrid(rex,rey,rez);

% Meshgrid creates a 3-dimensional coordinate taking in values 
% x, y, z

B = ((4*pi^-7)*(X.*sin(Y.*60)))./((4*pi)*(Z.^2));

% B is a multivariable function that takes in the values of x,y,z.
% It is the calculated magnetic flux density produced by a current
% carrying conductor.


for level = 0.2:0.2:0.8
    isosurface(X,Y,Z,B, level);

    % isosurface is MATLAB function used to plot the dependent variable
    % with all the independent variable (X,Y,Z) into a surface plot
    
    % The function or keyword level the a MATLAB feauture to denote
    % the gradient level used in the color bar 

title('Magnetic flux density')
xlabel('Amp (A)')
ylabel('Time (s)')
zlabel('Distance (m)')
cb = colorbar;
    % properties of the graph
end

quiver3(X,Y,Z,B) % <--I AM GETTING THE WARNING HERE

[KSSV]

Where have you used quiver3 ? Why you are using a meshgrid on a matrix?