MIT uses a weird class numbering system. Instead of CS101, they call it 6.0002.

The first digit is the school that offers it, then after the decimal point they have their number of classes. (EECS is unusual in that it has four digits after the decimal point, most every other course has just three.) In general, classes that are required start with 001 and increment up, such that 001 is the intro course, 002 follows from that, etc. Then electives start around 015 or so.

Course 1 is Civil Engineering, Course 2 is Mechanical engineering, Course 3 is materials science, etc. 6 is Electrical and Computer engineering.

So 2.009 is a mechanical engineering course, in this case one for students towards the end of their time. It's called Product Engineering Processes, where you create a new product from beginning to production.

2.009 appears to be some kind of class id. The actual class discussed was in 2017.