Dear All, How to customize this Summary card in the Sales order record. Could you please help me? Thanks

it can not be customised.

What end result are you trying to accomplish?

@Patrick A. Sir, I saw this post https://www.cloudcompasstech.com/netsuitegeek-tip-7-customize-netsuite-transaction-summary/

@Khon Mike yes, you can do that but that kind of customisation is not supported by NS. Actually, you can pretty much customise NS using jQuery but it will be at your own risk.