F

fill handle
a small black square at the bottom right corner of a selection
formula
An expression that calculates something, usually based on the values in cells. The formula = SUM(A1, B1, C1) adds the values in the three cells. The formula =D2/G4 divides the values in cell D2 by the value in cell G4.
Format Cells…
A command that opens a dialog where you can set formatting in selected cells for fonts and numbers.
Format Painter
Clicking the Format Painter button changes the pointer to the Format Painter shapePointer: Format Painter. The formatting of the current cell is copied. When you click on another cell, the copied formatting is applies.
Formula Bar
A text bar at the top of the sheet. It shows what the currently selected cell contains. If the selection contains several cells, the Formula Bar shows what is in the upper left cell. If a cell's value is calculated with a formula, the Formula Bar shows the formula but the cell shows the value, unless you are in Edit mode.
Freeze panes
A command on the Window menu which makes the rows and columns above and to the left of the selected cell "freeze" in place when you scroll the window.
Full screen
A view which maximizes the amount of screen available for the sheet by hiding the toolbars, statusbar, etc.
function
a mathematical expression. In the case of spreadsheets, a function always starts with the equals sign, =. 

Examples: =SUM(e12:h22)    =COUNT(b14:g36)    =AVERAGE(A4,A6,A12,A42)