You don't get a screen like the one in the screenshot below when you click the actual number on the screen?
Many of the numbers in that section do get pulled from other sections (such as W2s) so you won't be able to make direct edits - but you should be able to see the source numbers.
As for what the number consists of - it summarizes ALL of the taxes you have paid either directly or through withholdings on Forms such as W2s, 1099s, etc for both your federal and state returns. For example, that number would include both of your Federal and state withholdings from your W2s. It can also include local taxes, refunds applied to this year's taxes from a prior year, balances due from prior years that were paid in this year, and payments made with any extension you might file.
While it shows under Deductions and Credits, it’s actually just a summary number and not necessarily related to any particular deduction (some of it is not even a deduction - i.e. federal taxes withheld on your federal return).
