[vba] Meaning of .Cells(.Rows.Count,"A").End(xlUp).row

The first part:

.Cells(.Rows.Count,"A")

Sends you to the bottom row of column A, which you knew already.

The End function starts at a cell and then, depending on the direction you tell it, goes that direction until it reaches the edge of a group of cells that have text. Meaning, if you have text in cells C4:E4 and you type:

Sheet1.Cells(4,"C").End(xlToRight).Select

The program will select E4, the rightmost cell with text in it.

In your case, the code is spitting out the row of the very last cell with text in it in column A. Does that help?