This article is from the Apple II GNO FAQ, by Devin Reade with numerous contributions by others.
A#3.3: When you see something like "ls(1)" in the documentation, it refers to something called "ls" which is documented in Chapter 1 of the manual pages. Similarly, "select(2)" is refering to something called "select" which is documented in Chapter 2. To find out what the various chapters are for, type in the command man 4 intro substituting "4" for whichever chapter you wish to learn about.
 
Continue to: