Hi Holy,
First u need to decide which ver of DLP u wanted to implement like ver 11.1, ver 11.5 or 11.6 etc. then u need to decides which componenents u wanted to implment as there are Enforecr server, Oracle DB, Network Monitor, Network Prevent, Endpoint Server,Data Insights and Network Discover,Protect etc. Among these components u need atleats Enforce ,Oracle DB and optional Network components or Endpoints/other. etc. Depends of Budget and licence u purchase.
I am also attaching req. guide and snapshot for ur refrence. Also let me know what further system req. u wanted know.
Regards
Kishorilal