Bonds/Debentures are called debt. The benefit of holding debt instead of equity "of the same company" is that if the company goes bankrupt the debt holders have legal claim on the assets of the company, which means once the debt holders are paid off the rest is divided among the shareholders. - This means lower risk.
However profit is also distributed in the same manner - first the debt holders are paid as per the coupon rate and the rest of the profits are shared among the shareholders. - This means lower return as well.
You can use debt to achieve the desired risk/reward ratio for your portfolio. But since the debt market in India is not that developed. Maybe you can look at debt funds, they are a lot less complicated than trading in bonds directly. Something like mutual funds.