Sahej Paath or Sadharan Paath or even "Khula Paath" literally means easy or simple recitation. It is a Paath (recitation) which can started and ended at any time; with as many or as few people participating as desired. The recitation of the Sri Guru Granth Sahib is started at the beginning of the Granth Sahib and the whole of the 1430 pages of the Guru Granth is read in a slow fashion over from 7 days to in some case over several months. It is a slow and non-regular, non-urgent reading of the whole of the Guru Granth Sahib.
It is a good time to practice pronunciation and study meanings. Someone can even listen and correct the reader during the recitation. Anyone can perform their own Sahej Paath. This is normally the way the beginner would do the first few paaths of the Guru Granth Sahib.