If you're a student at Sheffield Hallam, then you can probably take part. Any 'full member' of the Union can run for a position in the election, and as a student you are a member of the Students' Union. This means that, whether you study full- or part-time, are a mature student, international student, Undergrad or Postgrad, you can take part.
International students studying for a Sheffield Hallam degree are eligible to run and vote for any position (not just International Students' Officer!)
There are a few exceptions you should be aware of:
Unfortunately, exchange students are unable to run in the election; Sheffield Hallam needs to be your 'main' University of study. Exchange students can still vote, though.
Some students 'opt out' of Union membership - if you've done this, then you will have to opt back in to take part.