These are schemes offered by some employers that provide pensions for their employees based on the employee's salary and years of service. They are sometimes called 'defined benefit' or 'final salary' schemes. The employer contributes to the scheme and there are trustees who look after scheme members' interests.
You should get an annual statement from the salary-related occupational pension scheme you belong to in your current job. This will show how much retirement pension you have built up so far and the amount you might build up if you carry on in the scheme until retirement.