Bonds are the loan documents of financiers. You lend money to some institutions to use this investment, and they will give you the sum of principal and interest. Bonds are "IOUs".

The statement that bond risk is relatively small, I think it should simply refer to national debt. The government supports bonds issued by the state. Of course, the risk of not paying you back is relatively small, but the corresponding rate of return is also low.

Generally speaking, bonds should also include corporate bonds. It can't be generalized as a small risk, it depends on the scale and operating conditions of the company, and some are high-risk.