Can I match two tables in postgresql, sum the data in the number column and create a new column?
As Lennart suggested, you should start with working example, which would help us better understood what the problem is, and what you need to be done. And please use english names in columns and table names.
(I wanted to response in comment, but apparently I have too less reputation to do that).
Basing on you description, though, it seems like simple join between these two tables, like:
select * 
from depoyaeklenecek d1 
inner join depoadetleri d2 on d2.kapino = d1.kapino

Going further, you should specify what to you understand by

collecting the data in the column &quot;adet&quot; - do you want to aggregate (sum?) them somehow? Or just fetch them to be used later?
refreshing my table in a way that I can write the number - do you mean that you want to update values in one table by values from the other one (per proper kapino number?) Or just want to sum these values and put them (where?)