I'm assuming you have a table called "Employees" or some such that's linked to this "Leaves" table?

If so, in your "Leaves" table, add a formula field with "WORKDAY_DIFF()" to get the number of workdays each record has

After that, in your "Employees" table, add a rollup field to sum up the values from the formula field we just created.  This should give you a total count of the number of work days the employee has applied for leave

Thank you Adam!

My Airtable forms has many enteries with the same names, hence, I'm not sure how to link the different entries to the Employees table. At the moment, when I tried to link it, it's only linking to one record each time (not all the records under the same employee). 

Any suggestions?

That's odd.  Let's say you have a record in the "Employees" table with the primary field value being "Bob".

In the "Leave" table, if you paste "Bob" into the linked field to the "Employees" table for any of the records, those records will then be linked to that one "Bob" record, it shouldn't create any more records

Could you provide some screenshots of the "Leave" or "Employees" tables, as well as the automation (if any) you're using to link the "Leave" record to "Employees"?

If you could provide a base with example data that would be best