Fetch the value to a number column A in one list from another number column B in another list. Add the values to column A each time an entry is made.

[Syndicate_Admin]

I have an invoice column a, in List A, which needs to fetch the value from Paid column b, in List B. Also, need to add the value to column a, each time an entry is made to column b. 

[ImkeF]

OK, so it popped up in the Power Query forum for Power BI here.
But re-reading your question, I get the impression that you need to create a solution in Power Automate for it:
There you have triggers that react to items being added to a list in Sharepoint. Something like this doesn't exist in Power Apps.

[ImkeF]

Hi @Syndicate_Admin ,
which program is this question related to?: Power Query (in Power BI) or Power Apps?

[Syndicate_Admin]

powerapps

[ImkeF]

Hi @Syndicate_Admin ,
I don't understand your request.

Please read the guidelines on how to post your questions to get them answered quickly and correctly:: help how to get your questions answered quickly - Microsoft Power BI Community 

[Syndicate_Admin]

I basically have two lists. The first list is used to pay invoices and has a column "total Paid" as displayed below:

Whenever i pay an amount in total paid for a particular vendor, it should save in another list with Column Name "Invoice Amount Paid". 

However, there can be multiple payments made to a vendor. So i need the payments to be saved in "Invoice Amount paid" and also get the new payments added to it.