How it's calculated
Property tax in Florida is collected by the county, not the state, and is calculated as a percentage ('millage rate') of the property's assessed value as determined by that county's Property Appraiser. That's why the effective rate varies from county to county — there's no single statewide rate.
Unlike income tax, Florida has NO state personal income tax — one of the reasons it's often mentioned as a tax-friendly state. But property tax does exist and is a real recurring cost you need to budget for every year.
The 'homestead' exemption (and why it doesn't apply to you)
Florida offers an exemption called 'homestead exemption' that reduces the assessed value (and therefore the tax) for owners who use the property as their PRIMARY RESIDENCE and are Florida residents.
As a foreign buyer who doesn't reside in the property as a primary residence, you typically do NOT qualify for this exemption — so your effective property tax tends to sit at the higher end of your county's range, not the average that includes homesteaded owners.
What to do before buying
Never assume last year's property tax as an exact reference for the future: in Florida the assessed value can be readjusted when the property sells (sometimes to the sale value), which can raise the new buyer's tax above what the previous owner was paying.
Check the specific county's Property Appraiser website (each county has its own, publicly accessible) to see the tax history of the exact property you're interested in, not just an area average.