Translation:The students did not listen to what the professor said.
For anyone else who was confused about why the past tense of "to say" in this sentence is "sade" when another sentence gave it as "sa", I found a helpful explanation at https://hinative.com/en-US/questions/156197. It sounds like sade is the more formal version and sa is the version more likely to be used in everyday speech, but they are both acceptable past tense conjugations of "att säga." ...Maybe one could draw an analogy to "going to" (formal) and "gonna" (everyday spoken version) in English (or maybe that is just more confusing to think about). Anyhow, in case someone else had my same question, I hope that helps! (And if that is not right, please chime in, some wise native speaker.... tack!)
You're talking about the American use of professor here, not the Swedish.
There's no real counterpart to the British academic title lecturer in Sweden, but the closest one would be lektor. In Swedish, en professor is not just more or less any academic teacher like it can be in the US. It is the highest academic degree and it should correspond to British professors.
In Sweden, nowadays you have to be a "doktor" - have a PhD degree - for almost any kind of employment at a university, and certainly for a permanent position. Being a "doktor" is a necessary, but not sufficient, condition for being a "professor". Only a small fraction of academic people end up as professors.