Effective allocation of resources in economic principles

"The effective allocation of resources means that under this resource allocation condition, no one's situation will get better without hurting others.

The meaning of this sentence is actually the same as Pareto optimality.

In other words, no one can become better without harming the interests of others. In other words, the allocation that does not harm others is the effective allocation of resources.

I haven't read your book. I'd better type out the examples in detail.