Is SLAT applicable for 3years law course after completion of B.COM degree?

Hello Shivani, the 3 year LL.B course you are seeking for is offered by Symbiosis Law School, Pune only.
For the admission into the college, you need to clear All India Admission Test (AIAT) of Symbiosis.

It is a full time, 3 years course (English medium) with only 60 seats.

Reservation of seats
SC - 15%
ST - 7.5%
Differently abled - 3%
Wards of serving/retired defence personnel - 5%

Over and above 60 seats
Kashmiri Migrants - 2 seats
International Students (PIO, NRI) - 15%

Eligibility criteria
1) The candidate must be graduated from any recognised university with 45% marks without any compartment ( 5% relaxation will be provided to SC / ST category)
2) Candidates in their final year can also apply, but they should provide their passing certificate by the date given.

All India Admission Test ( AIAT )
1) A test will be conducted to check your writing skills - Writing Ability Test (WAT) on the current topics.
2) A Personal Interaction will be there, in order to assess your attributes, personality and legal aptitude.
3) It will be conducted on 31st May, 2019.
4) The last date to apply/ register for AIAT is 21st May, 2019.

Visit the link I am providing to register for the entrance examination,
https://www.symlaw.ac.in/admission-procedure-2019

All the best!
I hope this helps.