In ruby console, how to update instance variable?

I have a model named "Person". In ruby console, I first declare an instance of Person, then I update the attributes, then save.

person = Person.last
person.name = "jeff"
person.save

After doing these, I got message like this:

   (9.9ms)  BEGIN
   (7.5ms)  ROLLBACK
=> false

What are "BEGIN", "ROLLBACK", "false" refers to separately? I googled, but nothing came out.