MyBB Community Forums

• Enable search engine friendly URLs?
  
• Use GZip Page Compression?
  
• Send Standard Headers
  
• Send No Cache Headers
  
• Friendly Redirection Pages
  
• *NIX Load Limiting
  
• Output template start/end comments?
  
• Enable XMLHttp request features?
  
• Use PHP's Shutdown Functionality
  
• Advanced Stats / Debug information
  
• Uploads Path
  
• Use Error Handling
  
• Error Logging Medium
  
• Error Type Medium
  
• Error Logging Location
  
• Enable Forum Jump Menu?
  

There is a description under each of the item's name. They are pretty sufficient. If you still have questions, please post up what you part of those descriptions you are not understanding

Or you can read the wiki

http://wiki.mybb.com/index.php/Admin_CP_...on_Options

Basically: if you don't know them, you probably don't need to change them from the default.