Basically excel is a spreadsheet that allows for entry of data, data manipulation, calculations, formatting, print outputs, customise sheets the way you would like and more
excel has very useful functions like sum, average, max, min, Rank, count, countif among others.
in excel data is entered in cells. the cells are referenced using there position such as B5 where the column is B and row 5.
when referring to a cell its reference must done properly otherwise errors are likely in excel.
Excel has other useful features like auto fill, hide columns, print headers in all the pages, print grid lines, freeze panes among others.
Visual basic editor is a feature that helps in designing user defined functions that are not inbuilt, this requires some knowledge on visual basic
The links below provide tutorials on some useful excel tutorials which are completely free. feel free to click any link and learn