To add a vertical line to a horizontal bar chart in Excel, you can follow these steps:

1. Select the chart by clicking on it.
2. Click on the "Chart Elements" button (the plus sign icon) that appears next to the chart.
3. Check the box next to "Axis Titles" to add the axis titles to the chart.
4. Click on the vertical axis to select it.
5. Right-click on the vertical axis and select "Add Vertical Line".
6. In the "Add Vertical Line" dialog box, select the type of line you want to add (e.g. solid line, dashed line, etc.).
7. Enter the value where you want the line to appear on the vertical axis.
8. Click "OK" to add the line to the chart.

To add a vertical date line to a horizontal bar chart, you can follow these steps:

1. Create a new column in your data that contains the dates you want to add to the chart.
2. Select the chart by clicking on it.
3. Click on the "Chart Elements" button (the plus sign icon) that appears next to the chart.
4. Check the box next to "Axis Titles" to add the axis titles to the chart.
5. Click on the horizontal axis to select it.
6. Right-click on the horizontal axis and select "Format Axis".
7. In the "Format Axis" pane, select "Date Axis" under "Axis Type".
8. Select the date format you want to use.
9. Click "Close" to apply the changes.
10. Click on the chart to select it.
11. Click on the "Insert" tab in the ribbon.
12. Click on the "Shapes" button and select the line shape you want to use.
13. Draw a vertical line on the chart where you want the date line to appear.
14. Right-click on the line and select "Format Shape".
15. In the "Format Shape" pane, select "Solid Line" under "Line Style".
16. Adjust the line color, width, and other settings as desired.
17. Click "Close" to apply the changes.