Hello!
Thanks for being a part of the community! 
We report positions of cells - not cell towers. The 65k+ records in the Spain list are list of cells. Each cell tower can have multiple cells.
A quick overview of the columns is here.
- To understand the telecom firm operating a particular cell, you’ll have to look at the ‘_Net: Mobile Network Code’. You can cross verify that number with the entire MCC-MNC list here
We receive positions of cells from the community. There are thousands of enthusiasts/ developers/ small to medium firms who send scanned info from their devices. These data points are called measurements. We process measurements to find positions of cells.