Answer:
It's describing advocacy, which it says is taking action to change what already exists into what it should be like.
Explanation:
For example, looking at the climate crisis:
The "what is" is our planet hurt by soil, air, and water pollution, fundamental resources being depleted before they can be replenished, biodiversity dying, global warming increasing, people's needs not being met, and more.
The "what should be" is a healthy planet and society that is not afflicted by the above, or if it is, as minimally as possible.
Advocacy is, in this case, the people speaking out and calling for change to turn what there currently is (the hurting Earth) to what should be (the not hurting Earth).
Hope this clears things up!
