Pension Credits is an income-based benefit and consists of 2 parts, 1) Guarantee Credit, 2) Savings Credit.
Guarantee Credit is an income top-up benefit. If your weekly income is below £159.35 (single people) or £243.25 (couples), Guarantee Credit tops up your weekly income.
For people who saved some money towards their retirement (as a pension for example), Savings Credit is an extra payment.
If you reached the State Pension age on or after April 6th, 2016, you may not be eligible for Savings Credit.