What exactly does it mean when you say frequency not reported under side effects?

If a side effect has the words "frequency not reported" then this means that neither the product information nor clinical trials have specified exactly how many people have experienced this side effect for this particular medicine.

Sometimes side effects are not reported until after a drug goes to market. When this happens, there is no way to know how many people have experienced this side effect reliably, and the side effect will usually always state "frequency not reported". This is because you would have to ask every single person taking that medicine in the world if they have experienced this side effect.

This type of data is not collected unless it has emerged that this is a side effect of concern and the medicine is being monitored by the FDA Adverse Event Reporting System (FAERS). Even then it will only be an estimate.