Below are few System Requirements for SharePoint 2016:
Scenario  Deployment type:
=====================
Processor
RAM
Hard disk
Database server running a single SQL instance
====================================
 Development  64-bit,
 4 cores
 12-16 GB
 80GB
 Database server running a single SQL instance
===============================
 QA/Production  64-bit,
4 cores
16-24 GB
  80GB  
Web server or application server in a three-tier farm
===================================
Development  64-bit,
 4 cores
 12-16 GB
 80GB
Web server or application server in a three-tier farm
====================================
 QA/Production  64-bit,
 4 cores
 16-24 GB
 80GB   

SPWebApplication- WebApplication
SPSite-Site Collection
SPWeb-Web
SPList-List
SPListCollection-ListCollectioon
SPListItem- List Item
SPListItemCollection-List Item collection