'Productive' is used to describe something that produces, or is able to produce, a large number of things. 'Non-productive' is the opposite. It describes something that does not, or is not able to, produce a large number of things. You can also use 'unproductive' for this.
'Productive' can also be used to describe something that produces a satisfactory result. In this use, the opposite in 'unproductive' only, not 'non-productive'.