An Excel table is a named data range with a header for every column. Select the data, then choose Insert > Table or press Ctrl+T. Keep My table has headers selected when the first row already contains column names. If it doesn't, Excel inserts names such as Column1.
The Table Design tab appears when a table cell is selected. Give the table a useful name, choose its style, or turn on Total Row. Each total cell has a function selector. Those totals use SUBTOTAL, so filtering a table changes the visible total.
Structured references use names instead of cell addresses. Supplies[Amount] means the data in the Amount column; [@Amount] means Amount in the current row. New rows become part of the table when you type directly below it.