Non-Covered Pensions are pensions from work where Social Security taxes were NOT deducted from your paycheck. Only certain government and foreign pensions are non-covered pensions.
Your receipt of a non-covered pension can affect your Social Security retirement benefit through Social Security's Windfall Elimination Provision. Also, your non-covered pensions will affect the amount of spousal and survivor benefits you can receive based on your partner's earnings record via the Government Pension Offset provision.