Disability insurance is designed to cover you in case injury or sickness prevents you from earning an income. You still need to pay mortgage, rent, and other monthly payments/debts, which is why it's important to have disability insurance. Disability insurance is especially important if you're the main income in your household.
Disability insurance plans are quite flexible and can be tailored to your needs, but the most common plans provide monthly payments to you after a 90-day waiting period and can continue for 2-years, 5-years, or until age 65. The waiting period can be changed to 30-days, or 60-days, and some insurance companies even offer instant coverage.
In case you decide to get disability insurance, but never end making a claim for the benefit payment, there's an option called 'Return of Premium'. You have to decide to get it at the beginning of your policy, and it increases the cost of your policy, but every few years you're able to withdrawal a portion of the premiums you've paid into it.
Every insurance company structures their plans a bit differently, so if disability insurance is something you're looking for, it's best to set up a meeting to discuss your options and find a plan that best suits your needs.