Dear Aki
Assuming you are holding the shares in demat account, your transaction of sale of shares before completing 1 year from the date of purchase will be exigible to STCG @ 15% + Surcharge (if applicable) + Cess.
Since held in demat form, the cost of acquisition for the purpose of computing STCG will be computed following First in First Out (FIFO) since you are selling only a part of your holdings. However, if you have bought all the shares in a single lot or the same date or all the shares at the same purchase rate, then there is no need to apply FIFO as the Cost per share is same for all the shares.
In case your taxable income Less: STCG is less than the exemption slab, you can take the benefit of Sec.111A of unused exemption slab.
In case, it is possible for you to hold the shares till the end of this financial year so as to complete 12 months holding period, you can generate teax exempt Long Term Capital Gain. However, caveat, for one, you can't predict the stock market and secondly, you have to make a cost-benefit ananlysis of postponing your principal repayment of loan (?).
Regards
Ajay