For bottle service reservations, a minimum spend is the amount of money you need to spend on alcohol and/or food in order to reserve your table for free. For example, if it says $1k min spend, you will need to spend $1000 on alcohol (usually 2-3 bottles) in order to get your table for free.
The table is NOT a separate purchase. Your final spend will be determined by the amount of tax/tip/venue fees added on to your minimum spend (anywhere from 20-38% depending on the venue).