The functions in Excel do most of the current work and there are functions to do many things.
The function can have parameters and you have to respect the rules of it.
If you press the equal sign it will show you a helping page explaining each of the parameters of the function and allowing you to ask for extra help.
You may create your own functions in VBA and use them where you want.
Functions in Excel are the basis of data manipulation.
The functions more used in some cases have more than one way to be done.
SUM, COUNT, MAX, MIN
The search functions in Excel allows to find values in the spreadsheet.
INDEX is the most popular function.
The error functions are used to check the validity of cells or properties of these cells.
ISERROR, ISNUMBER or ISTEXT are same samples
You can define areas of excel as tables and there are some functions to work with these tables like databases.
It allows you to find the value of a cell inside a certain block.
Is used more to retrieve a certain column from a record in a block.
Your block may be defined with a name or absolute coordinates in order that you can copy the formula to other place and keed the reference to the same block.