Bonds are in a simple terms an IOU issued by either companies or governments to borrow money from you. And like most IOUs, they will come with a promise or guarantee of the amount and time they will pay interest on the amount you lend them.
You can trade, buy and sell Bonds when you are looking to manage your investment portfolio, which makes this one of the more interesting investment products.
Due to its relatively lower volatility compared to equities, bonds can add stability and diversity to your portfolio.