Best places in South America to stay/visit on a work placement!

Hello everyone!

22F Londoner here. I'm currently at university studying Spanish as part of my degree - and in my third year there's an option of working abroad for six months.

I'd love any recommendations, taking into account safety, ease of transport to safe neighbouring cities/countries adequate jobs that would sponsor my teaching visa, etc. It's a year before I go, and I'm currently working towards a TEFL certificate, so will have certification to back me up.

Thank you!