LANE: Just don’t let her [Lorelai] change the date [of her wedding].
RORY: Not going to happen. Max is teaching a summer course at the University of Toronto, so if you’re back by the end of the summer, it’ll be fine.
The University of Toronto is a public university in the city of Toronto, Ontario. It is one of the oldest universities in Canada, and is the highest ranked university in the country, named among the best in the world. First founded by royal charter in 1827 and controlled by the Church of England, it changed its name in 1850 after becoming a secular instiution.
The university’s summer programs take place over 3-6 weeks, which fits in with Max being away until early August (so in fact the wedding could be moved up, causing Lane to miss it). Presumably Max is teaching classes in English Literature.
Gilmore Girls was first filmed in Unionville, on the outskirts of Toronto, so this seems like a gesture towards the show’s beginnings (at one time, they considered filming the show in Toronto permanently).