If you have a 2-dimensional spill range in Excel and you need to add up a specific column here is an easy formula to use.
In the image below I have used a SEQUENCE function in cell B2 that creates a 2-dimensional spill range.
To add up the third column in this spill range we can use the following formula (cell H2).
=SUM(INDEX(B2#,,3))
The INDEX function extracts the third column from the spill range and the SUM function adds that column up. By leaving the second argument blank in the INDEX function you are telling Excel to extract the whole column.
If you needed to add up more than one column, you can use the CHOOSECOLS function. If you wanted to add up the third and fourth column you could use the following formula
=SUM(CHOOSECOLS(B2#,3,4))
You can use the CHOOSECOLS function to add up a single column. I prefer the INDEX function for single columns as it is shorter.