I am waiting for the answer for my Question bearing No. 51586 regarding speech shortly before the start of Jumu'ah Khutbah especially in the language other than Arabic. We are eager to know the answer to this question.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

There is no objection in giving a lesson before Jumu'ah sermon if the objective is to remind people of the right and warn them against the evil as long as this does not cause any disturbance to the people praying.
This also should not be done regularly and should not be considered as a form of worship that should be done on Friday. In fact, neither the Messenger of Allah (Sallallahu Alaihi wa Sallam) nor the companions or their rightly guided successors were known to do such a thing.
Allah knows best.