If you own a property in the Czech Republic you are obliged to pay a property tax for another year by 31 May 2018. If you paid later (after 5 June 2018) you would receive a penalty from the Czech Tax Authority.
Regarding the payment details you should received a notice e.g. via email or letter within the past weeks. There should be mentioned the amount of your property tax and bank account details as well.
Generaly the property tax has to be paid for apartments, houses, villas, lands and some other properties so if you have not done the payment yet do it as soon as possible.