All the values of that particular line item, in all periods – the ‘whole row’.
You need to apply another function to turn those values into a single number. Most commonly, you’d use SUM or SUMPRODUCT.
SUM(ALLVALUES([Cash flow])) is total cashflow over the lifetime of the model – i.e. what would be in the row total.
SUMPRODUCT(ALLVALUES([Operational period flag]), ALLVALUES([Cashflow])) is the total cashflow in the operational period