Newtone is right. I have been to many of these. Those job fairs are attended by
1. Call centres, security agencies to attract non expensive labour. If there are banks there, they also mostly look to staff their call centres or front desks.
2. Employment agencies (non-profit) that mostly treat you like an ignorant individual, promising to magically transform your resume into a winning lottery ticket, but most of these advisors will not even have the intelligence to interpret your foreign credentials.
3. Government representatives fervently encouraging you to move to remote rural areas with "exceptional life quality"
4. Private colleges (that just got their accreditation) offering short expensive courses that promise you career success.
It does not hurt to go to these events as you will meet many other immigrants who may give you a useful piece of advice and you may get a survival job on the spot to get yourself into job market. I got a call centre job there - it helped me accummulate "canadian experience" and references who recommended me for my current "real" job.