Most of the responses in here are simply wrong. Numbers does support named ranges, in a way I find to be superior to Excel in most respects. What I like most, is simply entering values in the header row and column, also names the ranges, and the ranges are named including spaces, instead of replacing spaces with underscores. you don't need to type multiple menu commands as in excel.
To start, name your sheet (sheet name), then name your table (table name). In your table, set 1 or 2 header rows and/or header columns. You type the range names in these headers. The syntax can include spaces. The name selected is the rightmost or bottommost header cell with a value. Duplicate values in the headers are not allowed and take the syntax for formulas back to column letter row number.
For a multi row range - merge the header cells. For a multi column range - merge the header cells.
the naming syntax is: "sheet name::table name::colname rowname". the sheet name is not used on the same sheet, the table name is not used in the same table. if the column name is not specified, a row range is set. if the rowname is not set a column range is set. if your formula requires a a cell, you must specify a "colname rowname" that evaluates to an intersection of one cell.
the syntax is expanded somewhat when using applescript (and I assume Xcode). In the expansion, 2 header rows and 2 header columns can be used. For example, if the first header column contains file merged cells with the value "Gross Income", the syntax Range ("Gross Income") refers to a five row range, the width of the table. If you use another unique designator in the second header column, say (1,2,3,4,5), you can specify the syntax as Range ("Gross Income 2") and refer to the second row of the range alone.
to specify a column (or a range of columns) say "Value" Specify the syntax as Range("Value Gross Income 2). This will result in a range that is the row labeled "2" of "Gross Income" in the column or columns labelled "Value".
One thing I have discovered, is that there is an undocumented reserved word list, that will sometimes fail your formulas. if your names don't work in your formulas, try changing them slightly adding another letter or number to the end.