You will not see anything special if you only type an equal sign (=). After you type the equal sign, type the first letter of the function you want to use. You will see a drop-down list of functions that begin with the letters you type.
To see a list of all functions, look above the worksheet on the formula bar for the icon with the fx symbol. Click on that icon to see all the functions available.
Functions have a name followed by brackets. So when you have a name followed immediately by brackets, it is a function. On the worksheet it would also have an equals in front of it. In a module it would have the keyword Function in front of it.
Not in Excel.
yes
That is not a function of Excel.
Type an apostrophe first: '=
The Insert Function dialog box contains a list of predefined functions available in Excel. Click the Insert Function box, and in the search bar, type in a description of what you want to do. Click OK, and then browse through the functions. If you already know the name of a function, choose it from the box.
Formula autocomplete
formula auto-complete
A formula.
The SUM function would be the most commonly used function in Excel.
Without it, Excel will treat what you type in as a number, date or text. What you type will then literally appear in the cell. All functions start with letters. If the first thing you type is a letter, then it would be treated as text. The equals sign tells Excel to do the calculation that follows it. If you try typing any formula or function without an equals sign it will just appear in the cell and not do a calculation.
When you choose the Insert Function command and then pick a function to use, it will appear so that you can type arguments into it.