You can backup individual tables if you want but it is a wiser move to back up your entire DB. Since BuddyPress relies on user data that is stored in WordPress tables, it is not a good idea to just back up BP tables.
Here are some basic instructions in the WordPress Codex.
https://codex.wordpress.org/Backing_Up_Your_Database
		
	 
	
	
	
 
		
			
	
	
		
		Jeff’s spot on; back ups are only useful when you need to restore from them; and I can guarantee that if you back up specific tables, you are going to kick yourself when disaster strikes and you realise that you need a table you didn’t backup 
		
	 
	
	
	
 
		
			
	
	
		
		 @jeffsayre  @DJPaul
Can’t wait see import/export like wordpress.  Useful for transfer, another install, etc.
		
	 
	
	
	
 
		
			
	
	
		
		 @intimez – Per BP Roadmap – BP 1.4 Import/Export of all BuddyPress user data
– unless of course someone makes a plugin for that function beforehand 
Even so, nothing beats database backups