You have simply no idea.
But…what it means is, “I am here in Florida, and I intend to make my residence in Florida” is good enough to register to vote. I can give you a good example of that I ran into registering people. I came across an extended family that is opening up/running a little BBQ joint down here. Just moved from AR. Only one of them had an address here, the others were staying with him or living in a hotel. But clearly they are intending to reside here…they are in various states of moving their stuff here, they are committed financially and employment wise to opening a new business…they are intending to live in Florida. And that’s more than good enough.
Some states require a person reside at a residential address for some specified times. Florida doesn’t. Merely stating you live here is good enough. Now, having an actual residence, a FL driver license, possibly a homestead exemption, and yes…being registered to vote…all help the case if someone does decide to question the legitimacy of your residency. But the state won’t on its own.