Incomplete question. I inferred from a historical perspective.
Step-by-step explanation:
Back in the days in which Native Americans also referred to as Indians faced discrimination, the term "Kill the Buffalo" was used as a mockery against the Indian tribes.
This is evident from the fact that nearly all Indian tribes at the time lived alongside buffalo herds and they used the buffalo skin for tents and their meat for food. So, it a sense, it was a campaign to kill (destroy) a precious resource of the Indians, namely, the Buffalo.