HI,
Terminal is one of the Utility apps that Apple supply with the Mac in Applications/Utilities (That is open the Applications folder then the Utilities one).
Whilst the User Interface of the OS is referred to as high level (all flash and icons and hardly any visible code like things) the other end (code only) is referred to as Low Level.
Terminal is somewhere in between but closer to Low Level.
If you are used to windows and doing things in the Command Line then this is what Terminal does.
It is not something you can play with to learn how it works.
It is very easy to break the OS this way.
Some of the instructions used can appear very code like.
They can be very specific about the Spaces and the case the instructions are written in.

9:12 PM Wednesday; November 21, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
 iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images."  No, Seriously