Mid()

=mid(text,start no,num char)

This formula is like left and right formula
but it pick the no. of digits you define from/after the digit number you tell.

Text= Cell number
Start no= From left from which digit you what to start.
num cha= Number of Characters from the start no.

Networkdays()

=Networkdays(Start date,End date,Number of holidays in a week)

This Formula will help to get number of working days for a defined period.

Offset Formula

=Offset(A2,2,3)

This formula will take you to the cell which is 2 rows down and 3 columns right. Very useful for automation as 2 and 3 can be replaced with cell no. Whatever you want.

For going to upper row and prior column -1 / negation number can be used

Len()

=Len(cellno)
This formula helps you to get number of digits/alphabet/special character in the cell selected.