If you have public health insurance, you must pay for long-term care insurance (Pflegeversicherung). It pays for your healthcare when you are old.
Pflegeversicherung costs 2.6% to 4.2% of your income. If you have a job, your employer pays 1.8% and you pay the rest.
German health insurance calculator
If you have private health insurance, Pflegeversicherung is included in your insurance policy. The cost is set by the company. It’s not a percentage of your income.