Line 13000 - Other income contains taxable income not included in other categories. Common sources of other income include scholarships/bursaries, retiring allowances, lump-sum payments, death benefits, and payments from a Registered Education Savings Plan (RESP).
Other Income amounts can come from many different places, including Box 66 or 67 from your T4 slip.
This Canada Revenue Agency (CRA webpage has more information on Line 13000 - Other income: Line 13000 – Other Income