This example uses both an INNER JOIN (to update the values in Table1 with the corresponding values from Table2) and aliasing for readability.
I added the additional parameters in the WHERE for illustrative purposesUPDATE t1
SET t1.Column2 = t2.Column2
FROM dbo.Table1 t1
INNER JOIN dbo.Table2 t2
ON t1.Column1 = t2.Column1
WHERE
AND t1.Column3 = value
AND t2.Column4 = value