A qualified retirement plan is a plan that is governed by IRS rules. It is a plan in which either the contributions or the earnings (or both) are exempt from tax. Typically, these plans come from employers or have custodians (like a traditional IRA) that ensure the IRS rules are followed. Nonqualified plans can be annuities purchased from insurance companies or employer plans that allow larger contributions than the IRS permits.
A contribution to a qualified retirement plan - typically either an IRA or an employer plan - would enable you to get a saver's credit if your income is within the allowable range.This IRS page summarizes the Retirement
Savings Contributions Credit, including what income qualifies for it.