Here’s how to install the extension and resize the label column:
1. Visit Gmail label column resizer in the Chrome Web Store.
2. Click the Add to Chrome button, then Add extension. Once the extensions has finished installing, you will see a notification in the top right corner of Chrome.
3. Open Gmail, or reload it if you already have Gmail open.
4. Look for the dotted vertical lines running down the right of the label column. Hover over these lines until you see the two-sided arrow mouse pointer. Click and drag the dotted lines left or right to re-size the column.