Can I set the min/maximum number of lessons per day for one class?

Yes it is possible to set min/max lessons per day for each class.

However please note that by default the software calculates this for you. If you have 32 lessons per 5-day week, then the software will allow 6-8 lessons per day. So setting the min/max is only needed when you want to override this automatic calculation or if you have turned it off.

Please read this article first. It shows you how you can overide the automatic teaching block calculation:
Education block - allow some classes to come later or to leave school earlier.

So if you use an automatic teaching block that calculates 6-8 per day, the software will not put 9 lessons per day. However you can specify that you want max 7 lessons. Go to menu Main/Classes/Constraints/Advanced:

Ok, Ok but I want to have min 5 on week days and min 2 on saturday.

In this case you have to define advanced card relationships that defines minimum lessons on one day and specify some days. It defines that you want minimum of 5 lessons on Mon-Fri: