Need to calculate SUM of certain values in one column depending on a value in different column in same row

I have data structure like following

No      Date       Name Vehicle     Finance
1001    01/04/2015  abc Activa       HDFC
1002    02/04/2015  abc Activa 125
1003    02/04/2015  abc Activa 3G    HDFC
1004    02/04/2015  abc Shine
1005    01/05/2015  abc Activa 3G
1006    01/05/2015  abc Dream Yuga
1007    02/05/2015  abc Unicorn 160

Now what I need is count of each vehicle for a certain month, say April. I was trying to do it something like this

=IF(MONTH('Sales Register'!C3)=4,COUNT('Sales Register'!A3:A5000),0)

But clearly it isn't the right way. How it can be done? Also if there is more complexity like I want to sum no of Activas which are financed for a specific month by HDFC, how will it be done?