The cost per click on your ad depends on the keyword used and is calculated by Google using an algorithm. The basic rule is: The lower the competition for a keyword, the lower its cost per click (CPC). You can view the CPC for each keyword when setting up your campaign. Just move the mouse over the circle with the respective keyword and the cost will be displayed.
Hint: Don't focus too much on how much your keywords cost, but rather think about what you would look for if you were a customer (don't worry, your maximum daily budget won't be exceeded). Don't be afraid to select a (good) keyword even if it is a bit more expensive. After activating your campaign, you can always monitor it and easily adjust your maximum daily budget or the selected keywords using the analyses on the overview screen.