Student or Learner
Is there difference in meaning between:
1. Teenagers should do more sports.
2. Teenagers should do sports more often.
In spoken English, the two sentences could mean the same thing.
"Teenagers should do more sports." The meaning of this sentence is vague. This sentence could also mean: "Teenagers should do more [kinds of] sports."
More is an adjective modifying the noun sports. It does not necessarily mean more often.
"Teenagers should do sports more often." This is a better sentence. You could also say, "Teenagers should play sports more often."