To sum entire column or row use the SUM function with the relevant column or row reference e.g. for the entire sum of column B, use =SUM(B:B) formula.
Excel recognized full column or row reference like this:
=SUM(B:B) means the entire sum of column B
=SUM(7:7) means the entire sum of row 7
Although, the ‘Sum entire column’ or row is a useful way to save time and add all data, however, extra data like dates etc. may include and create difficulties.