This question is about modelling mechanical response of behavior in terms of signals
I dont know what this axis([-.76 -.16 -15 5])’ means


As far as I am concerned axis([-.76 -.16 -15 5]) set minimal and maximum values for x axis (first and second values) and y axis (third and forth values) in plot.

For example:

x = linspace (-10, 10, 100);
y = x .^ 2;
plot (x, y, 'r', "linewidth", 2);
title ("S");
xlabel ("x");
ylabel ("y");




x = linspace (-10, 10, 100);
y = x .^ 2;
plot (x, y, 'r', "linewidth", 2);
title ("S");
xlabel ("x");
ylabel ("y");
axis ([-5, 5, -5, 20]);