If you want to know what the method does, then should read the NSTableView Class Reference and also the reference for the associated protocols.
If, however, you are confused by the fact that the method name has multiple parts separated by spaces then it helps to remember that method names in Objective-C consists of one or more labels and parameters associtated with them.
If the method name has just one label, it can also have an associated parameter. However, if the method name has more than one label, then each label has an associated parameter.
@interface Foo: NSObject
- (id)initWithBar:(Bar *)bar withFrame:(CGRect)frame;