What is meant by the expiation for an oath (kaffarat al-yameen) that is obligatory for someone who swore an oath by divorce without intending its occurrence?

Swearing by divorce (Al-Helf bi Al-Talaq) causes divorce to occur according to the majority of scholars if the oath is broken. The same applies to making divorce conditional (Ta'liq Al-Talaq). However, Sheikh Al-Islam Ibn Taymiyyah disagreed, holding that swearing by divorce or making divorce conditional, if divorce was not intended, only necessitates an expiation for an oath (Kaffarat Yamin).