Here's a step-by-step walkthrough on how to sum a column in Google Sheets
1. In a cell below your desired column, type "=sum" and press enter.
The formula would automatically consider the above values to sum.

2. If you want to sum the column in a different cell, then type "=sum" and press enter.

3. Then, select the values in the column and press enter.

Congrats! You have successfully summed a column in Google Sheets!