Meeting Jargon. Here 地 is like 地 in 脚踏实地, with the metaphoric meaning of 地 Meaning the thing can be carried out following foolproof steps. “落地有声” means sth falls and make a sound, metaphorically. So it is likely that the speaker demands an instant effect ( just like the sound an falling object makes when it collides with the ground) from this thing that is to be carried out.

可行性，可操作性。Feasibility、operability.

其实你这句话并没有给我们有价值的context， 如果你谈到落地性，我只能理解为你在谈论一个计划，项目的实际可操作性。这个计划，项目落地性很强。

Never heard of this saying, but a quick search confirms that Philip is correct about it.

Hello, 落地性 is kind of new business language being used in mainland China. It means something's realizability, especially like a plan. To make a theory or plan being applied in reality.