Complex sentence: The last two are MARS "Mandatory Academic Revision Session" and MASH "Mandatory After-school Study Hall" both of these are ways to help the student out if they are not doing as well as they should.
Split into simpler sentences: The last two are MARS "Mandatory Academic Revision Session" and MASH "Mandatory After-school Study Hall". Both of these are ways to help the student if they are not doing as well as they should.