the third value in recommendations corresponds to expert's prognosis regarding the return rate of a stock. Its meaning is slightly vague since we do not know what is the horizon of the prognosis.
If an expert says that the price is going to be A and the current price is B, then in the data, we report the value (A - B)/B as the prognosis. However, there can be some inconsistencies, e.g. imagine a situation when an expert says that the price is going to be A and then, after several days there is a split on this stock. The quotations (including the historical ones) are adjusted but expert's prognosis is not, so they become incomparable.
Moreover, not every expert shares his expectations regarding future prices of a stock (in those cases there is 'NA' in the data).
I hope that this explanation helps :-)