Pro Tem means the ‘for the time being’. According to the constitution, the Speaker of the last Lok Sabha vacates his seat immediately, before the first seat of newly Lok sabha. Then the President appoints a seniormost member of the Lok Sabha as the Speaker Pro Tem and administers him/her the oath.
The Speaker Pro Tem is vested with all the powers of the Speaker. He presides over the first sitting of the newly-elected Lok Sabha. His main duty is to administer the oath to new members. He helps the house to elect the new speaker.
When the speaker of the house is elected. the office of the Speaker Pro Tem ceases to exist. Therefore, the office of the Speaker Pro Tem is a temporary office which exists for few days only.