Parsley 'Hamburg' is a turnip-rooted variety of the plant. The 25cm root looks like a parsnip. It is cooked and eaten in the same way as a parsnip, turnip or swede. The leaves can be used in the same way as flat-leaf parsley.
Disclaimer: Plant notes found here are given in good faith and are for educational and/or gardening purposes only. Seek further information if the plant is unknown to you.