In principle, the electricity is not included in the rent, so you have to pay for it separately. You have to be careful when you register with an electricity supplier company - It is worth to research, compare different offers and find the best rate. Tariff calculators provided by websites such as Check24 can be very helpful in finding the best option. You can find a company and directly register on their webpage. When you register, the electricity company will ask you for the apartment's current power meter reading. You can find power meter reading on the handover protocol which you have received from the landlord or property manager at the start of your rental contract.
If you use gas for cooking or heating, you may also need to register with a gas supplier company. Your landlord can provide you with more information in this regard. Like electricity, you can compare the prices and register online at the gas providers' website. Visit Check24 to check different gas provider companies' tariffs.
Please note: Your electricity supplier company (and possibly also your gas supplier company) will deduct a fixed amount from your account on a monthly basis. The amount of this payment is calculated based on the company's estimation of your sum of use. Once a year, your actual electricity consumption is checked, and then you either will be reimbursed or have to pay some extra money. What you pay at the end of the year depends on the extent to which your consumption exceeded the company's initial estimations. Your electricity supplier company will contact you at the end of the year and ask for your current power meter reading to check your actual amount of use.