CALCULATED COLUMN

Hi SukanyaGG 

The solution depends on your data model. If there is a one to many relationship between the two, the one on the many end can use RELATED to return a column  value from the related table. If there isn't you can  use LOOKUPVALUE granting that the result returns only one distinct value - eg no multiple value for the same month. You can also use CALCULATE to get the data from the other table. Example

CALCULATE (
    SUM ( othertable[column] ),
    FILTER (
        othertable,
        othertable[lookup column] = EARLIER ( thistable[lookupvalue column] )
    )
)

SUM can be replaced with MAX, MIN, LASTNONBLANKVALUE, FIRSTNONBLANKVALUE, AVERAGE, etc.