Wa alaykum assalamu warahmatullah

In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon our Prophet Muhammad.

 It is obligatory to listen to the khutbah (sermon) on Friday in order to get benefit from the admonition. Therefore, it is totally prohibited to be engaged in any kind of talk or idle act while the khutbah is being delivered. The Messenger of Allah (peace and blessings be upon him) said, “Whoever says to his companion on Friday, when the imam is delivering the khutbah: ‘Listen attentively,’ has thus engaged in idle talk.” One may not even read the Quran or pronounce words of dhikr because he has to listen to the khutbah attentively.

However, if one cannot hear the khutbah or can hear it but it is in a language he does not understand, then he may get engaged in any kind of dhikr to make use of his time. But still has to be quiet and make no noise for those around him.

Allah Almighty knows best.