The “Active cell” is the cell where your cursor is currently placed in Excel. Sometimes you want your macro to start working from the active cell. Other times you want your macro to start working from a particular cell (e.g. A1) or do its work on a “Range” of cells. The active cell is the cell you’re currently in. See also S for “Select” which tells you how to select the active cell.
A also stands for “Argument”. Start worrying if you have too many with yourself. Here it has a technical meaning. To help you get your head around it we’ll make the comparison with Excel’s standard functions. To get a function to work within Excel it needs certain inputs or arguments. For example the sum function in Excel needs to be pointed to the cells that you want to add up: those cells are the inputs or arguments for the formula. The same is true in VBA. To get a piece of code working in VBA you can use the macro recorder (that will do all the hard work for you – remember we’ve shown you how to record a macro). If you move on and start modifying or typing in your own code that code is going to need to contain the right inputs or arguments. Also see under “VBA help”. VBA help usually contains plenty of handy information about the arguments you need to get your code working. Your code needs the correct arguments.