The State Pension age is the age at which you can receive your pension from the state.
This has started to change from age 65 to 66 (depending on when you were born) for both men and women. The increase to 66 will be completed by October 2020. In the future it will rise again to 67 and then 68.
If you retire before you get your State Pension, it’s worth checking that your other pension savings or income can cover your living costs until then.