Hi all 
I want to start using a 3D printer,and I realized that in part of the process there is something called “Slicer” [yes im newbie ]
do i have to lowpoly my models be4 i start the slice process\ printing?
or unless my model is 1.000,000,000,000 polygons all good?
You can use Decimation Master to crunch the polycount of your model down before exporting to your slicer. The practical polygon limits will vary by software, but ZBrush levels of mesh resolution are going to be far too high for most programs. I would aim for a file size of under 150 MB and a mesh polygon count of under 500k for compatibility with most programs. Some programs will be able to handle more than that, but the further you can reduce it while still keeping your detail intact the better it will perform.
Your printer device maker or printing agency, and the documentation for your slicer will all have more specific information about the limits of the software or process.