Hi,
In MoodleSpeak, I think you mean "courses" not "lessons". I made the same mistake when I first studied Moodle. I may move your question out of this forum but let me try to answer your question first.
In Moodle language, a Moodle site has courses. One course can be placed in a group of courses which is called a category. Students can enroll in (subscribe to) a course. Here is some more information about
site course categories.
Inside each course are
activities modules, resources and blocks. Activities and resources are placed in
sections (groups). These sections can be called "topics" or "weeks". A Lesson Module is an Activity module. Each Lesson can have a password. It is possible to make a student take the first lesson before taking the second lesson. You are not talking about this kind of lesson.
I think in Moodle language you are asking, "Can a student enroll in a category of courses? I do not want them to have to enroll in each course in a category, just enroll 1 time." I think the answer is "yes", when you set up some "
Metacourse" (please follow the link to Moodle documentation for more words).
People say it can be tricky to set up a Metacourse the first time for a new Moodle users. In theory here is how a Metacourse works.
A Meta course allows a student to enroll in one course and then automatically enrolled in other courses. This is what you want.
For example: in the "Use Words" category, you would make an "Introduction to Use Words" course. This would be the meta course or parent course. "Use Verbs", "Use Nouns", "Use Adjectives" are courses in the "Use Words" category. Once the student subscribes to "Introduction to Use Words" they will not be asked anything when then enter "Use Verbs" for the first time.
Hope this helps, Chris