This article explains how to add, remove, and otherwise customize columns in Google Sheets.
Freeze or Hide Columns and Rows in Google Sheets
Spreadsheets are made up of columns and rows. To use them effectively, it’s important to know how to modify them to include the information you want to track or the data you want to manipulate. To add a column to a spreadsheet:
Open Sheets as you normally would and open the spreadsheet you want to add columns to.
Decide where you want your column to be and hover over the letter at the top of one of the columns next to it. For example, here we want to add a column between D and E, so we hover over E.