As its name implies, single premium whole life insurance is a form of whole life insurance which can be paid for using a single, large premium. The premium paid normally matches the face value of the policy, so the cash value matches the face value from the beginning.
Your equity in the life insurance policy normally earns interest, and you may receive dividends if the insurance company performs well.
Single premium whole life insurance policies are normally used as an investment instrument (much like an interest-earning savings account). Building the full amount of cash value from the beginning is financially advantageous over building cash value over a long period because you earn interest on the full amount right from the start.
Because the entire policy is funded by a single premium rather than many small premiums, the administrative fees charged by insurance providers may be lower than those charged for other forms of whole life insurance.
A number of Swiss insurance providers offer single premium whole life insurance based on the pillar 3a and pillar 3b categories of retirement savings. However, unless you have legal reasons for wanting to get whole life insurance (as part of estate planning, for example), getting affordable term life insurance and using a savings account to save almost always works out cheaper than using a combined whole life insurance solution.
Swiss term life insurance comparison