Hi can someone explain what is meant by the inverse of a transformation

it is the transformation needed to return to the original state.

Just as an inverse function is what you need to get x.

sqrt(x) and x^2 are inverses because (sqrt(x))^2 = sqrt(x^2) = x

similarly, stretch by 2 and shift 8 up has the inverse transformation

shift down 8 and shrink by 2.

+ is the inverse of -
and so on.