Some Coursera courses are part of Specializations, a series of related courses designed to help you master a specific topic.
You can take individual courses in a Specialization without having to complete the entire Specialization. You will get a Course Certificate for every individual course you complete, whether or not you finish the rest of the Specialization.
If the courses allow you to pay individually, you can pay for each course you want to take without paying for the entire Specialization. If the Specialization requires a subscription, you can subscribe to the Specialization, take as many courses as you want in that Specialization, then cancel your subscription. You will still earn Course Certificates for the individual courses you finish.