Excel organizes information into a grid and can calculate with it — the difference between a list of numbers and numbers that actually add themselves up.
Columns are lettered — A, B, C… — and rows are numbered — 1, 2, 3… Each box where a row and column meet is a cell, named by its column then row, like B3.
One Excel file — a workbook — can hold several worksheets, the tabs along the bottom. Separate grids for separate purposes, all inside one file.
The small box in the top-left, above column A, is the Name Box — type a cell reference like Z100 and press Enter to jump straight there. Ctrl+Home jumps back to cell A1; Ctrl+End jumps to the last cell that actually contains data.