To skew means to slant at an angle. With SVG you can skew the x-axis or the y-axis.
To skew the x-axis, use the skewX(a) transform. To skew the y-axis, use the skewY(a)
transform. In either case you would provide as a parameter the angle in degrees to skew. The syntax
of the skew transform is shown below.
In experimenting with the skew tramsforms, I find that an element skewed along one axis greatly
effects the location of an element skewed along another axis on the same canvas. I don't know the reason
for this, but upon inspection of code generated by inkscape for placing oppositely skewed elements
on the same page, it uses the matrix transform instead.