Hello Patrick. It seems like you're using standard spreadsheet terminology so forgive me if I am misinterpreting but if I translate what you're saying into Airtable terms then it sounds like you want to only share a single Table within a Base. You can create a private link for a View and share it with only the people you want to have access. With an upgraded plan you can invite specific email addresses which is even more secure.

To set up a Share link simply click the Share View button on any View you want to share with someone.

Thx for your kind reply! But I thought i may mislead you with my poor description..

The real problem for me is I need Mr.A to add and edit data in SheetA, not only browse them. Im not sure if this is something the private link can manage.

Ahh! Will the data in SheetA affect data in the others? 

If not, a common practice is to make an entirely new base where Mr A can do all of his work which is populated from synced data from the base you don't want Mr A to be able to browse

Sadly it affects...basically what I need to achieve is let Mr.A only manage the cost part(his part of cost actually so I can still add cost data myself), without having the permission to learn about the profit part(which will calculate in sheetB using income minus cost)

You may need to create an interface that gives Mr.A access to only the info he should see and NOTHING he shouldn't. Then just give Mr.A access to the Interface but NOT to the base itself.