Hi tkrajutkraju,
Thanks for your post in Microsoft Community.
First task: Firstly, we need to create the data source for the dropdown lists. For example, create a new Sheet2.
In cell A1, enter this formula to format the date in column A of the original data.
=UNIQUE(TEXT(Sheet1!A2:A9,"mmm-yyyy"))
In cell B1, enter this formula to extract the Dealer IDs:
=RIGHT(Sheet1!B2:B9, LEN(Sheet1!B2:B9)-FIND("-",Sheet1!B2:B9))
In cell C1, enter the following formula to get unique Brand names.
=UNIQUE(Sheet1!G2:G9)

Second task: Create dropdown lists in cells H2 to J2, referencing the data sources created in Sheet2.

Third task: Using the SUMPRODUCT function might be difficult. I recommend using the FILTER function. Enter this formula in K2: =FILTER(C2:F9, (TEXT(A2:A9,"mmm-yyyy")=H2)(RIGHT(B2:B9, LEN(B2:B9)-FIND("-",B2:B9))=I2)(G2:G9=J2), "")

I hope the information above is helpful to you, and I look forward to your reply!
Best Regards,
Thomas C - MSFT | Microsoft Community Support Specialist