Hi Bavaliya,
Thank you for querying in this forum.
From your description, it seems that you want to set Validation settings in SharePoint list, however, you cannot use the formula correctly.
If my understanding is right, we’d suggest you use the formula below:
=OR(AND(ISBLANK([Approve Date]),ISBLANK(ABC1)),AND(NOT(ISBLANK([Approve Date])),NOT(ISBLANK(ABC1))))
And we have also tested it on our side, we went to SharePoint list settings > Validation settings > used the formula above, as shown below:
After setting it, we went back to SharePoint list and set the value of Approve Date column to blank and set value under ABC1, it will appear error below:
If the scenario above is not consistent with yours, you can also post back and point that.
Your understanding and patience will be highly appreciated. I hope that you have a safe and happy new year.
Best Regards,
Sukie