>>> At the foot of the window is a pale grew band
>>> with "Ready" at the left and just "Num" at the right.
That is the Status bar. If you type in a cell, it will show 'Enter' at the left until you have pressed Enter or moved to a different cell, when it will change to 'Ready', being ready for you to insert more data. 'Num' indicates that the Number Lock for the numeric keypad is enabled. If you press the Caps Lock key, you will see 'Caps' beside 'Num'. Similarly with the Scroll Lock key, you will see 'Scrl'. If you highlight a several cells with numbers in, the Status bar will indicate the sum of those cells.
The chevrons are used to scroll left/right when there are too many 'Worksheet' tabs to fit in the screen. > and < will go right and left. |> and <| will go to 'last' and 'first'.
Without seeing the file, I cannot answer where "Class List 20078 converted csv" has come from but the Excel may have been exported or imported at some time in its life as a .CSV file - a plain text file with data delimited with commas (Comma Separated Values).