Germination?

Okay. So this topic might have been discussed in the past, but I can't find it.

My question is: what does germination actually mean . . . to real people? I'm not interested in the science of things at this particular moment; I just want to know what it means when a seed packet says something like 12-14 days germination, for example. What visible thing should I expect to see in 12-14 days, if anything?

Ta!