You can actually do that through formatting. Select the column by clicking the column letter, go to the Format menu, to “Number”, then “More Formats” and finally “More Date and Time Formats”.
At the top, click in the right side of the dropdown area to put your insertion point there, and then just backspace to delete whatever currently exists. Then, click the drop down arrow and you’ll see the different types of date information you can add. Choose “Month” for instance and it will insert a ‘Month’ box with little arrows in it. Click the arrows and you can choose how the month is displayed. I choose “Month as full name”. Then type a coma and a space to the right of the month box you inserted, then click the down arrow and choose “Year”, and a year box gets inserted. I then clicked on the arrows and choose to have a 4 numeral year displayed. Click “Apply” and the entire column now shows dates like “March, 2021”. You can customize it any way you like this way.