Of course! From the Configuration> Ecommerce section of your backoffice you can choose whether your platform will be free or paid.

If you select the option "free courses", your users will be able to access the material of your courses without going through a payment gateway and consequently without paying.

If you select the option "paid courses" you will be able to put a price on your courses. If you want some of your courses to be free, you can put an amount of 0. Users will go through the purchase process but will not have to pay.