I used to live in Bologna and it's a fun place to visit - not touristy, but still more international than many cities of its size because of the university.
If you're there on a Saturday morning, absolutely go to the farmer's market in the courtyard of the Cineteca di Bologna, which has great artisanal products:
https://mercatoritrovato.it/ They had some interesting biodynamic wines - I will never forget this incredible pignoletto spumante we used to get there for the amazing sum of €6/bottle. I really got to enjoy the regional wines like pignoletto, lambrusco, and trebbiano, which are rarely seen where I like (west coast US).
I second the suggestion to tour the Torre Asinelli - from there I would wander down to Piazza Santo Stefano and tour the church complex there, which is a nice medieval architecture mashup. Really just aimlessly wandering around the historic center is a great afternoon!
If you want a taste of medieval student life, the
Osteria del Sole was founded in the 15th century and is shockingly unpretentious and chill. They serve good wine, you bring your own snacks, maybe an assortment of salumi from
Eataly (the original) or
Tamburini down the street.
Via del Pratello is a great evening walk, stuffed with bars and restaurants and live music venues.
The Museo della Storia di Bologna in Piazza Pepoli is a great museum that won't take all day (figure 2 hours), unlike a lot of Italian museums...
If you're into the modern culture game, the Cineteca has interesting programming, and
MAMBO is occasionally brilliant for modern and contemporary art.
To eat, obviously you should have a nice tagliatelle al ragù and tortellini in brodo while you're there. There are so many good osterie that can help you with these. Some less-known regional foods are the piada or piadina (similar to a quesadilla but with things like arugula, prosciutto, etc inside), and crescentine and tigelle, a fried bread and biscuit respectively that are eaten with mortadella, scquaquerone cheese, and other good stuff. Zerocinquantino, right off the Piazza Maggiore, is an easy place to procure the latter, if a bit posh.
Bologna is not famed for its pizza, but La Bella Napoli in Via San Felice is the best pizza spot in town and I'll fight you if you say otherwise.
NB: These tips are all pre-pandemic, I don't know how things have changed!