«فَكَفَّارَتُهُ إِطْعَامُ عَشَرَةِ مَسَاكِينَ مِنْ أَوْسَطِ مَا تُطْعِمُونَ أَهْلِيكُمْ أَوْ كِسْوَتُهُمْ أَوْ تَحْرِيرُ رَقَبَةٍ»
The expiation is feeding ten needy persons, or clothing them, or freeing a slave.
In the Qur'anic statement concerning the expiation of an oath, aw presents legally recognized alternatives. The particle does not itself require performing all three options together. One of the available modes can discharge the obligation subject to the applicable conditions.
This distinguishes the obligation itself from the alternative prescribed ways of fulfilling it.