Question

Why is work always done against something?

Answer 1

Work is done by something or someone, expending energy by exerting a force on an object. I'm not quite sure what the context is of your quote, but I'd imagine that it could be a scenario much like the following one:
Imagine a ball with some mass
m
being lifted by a man. The gravitational force from Earth is pulling the ball down, but the person nonetheless manages to lift the ball upwards. He expends an amount of work
W≥mgΔh
where
Δh
is the difference between the initial and final height of the ball. He has now done work against the gravitational force. I think you might be simply reading too much into it all.