Safe Harbour 1.0 was a set of principles that United States companies had to comply with when they were processing personal data of European citizen. It is about the transfer of personal data of EU citizens to the United States.
Think about Facebook. To comply with Safe Harbour Facebook had to make sure United States authorities like NSA could not spy on personal data.
In a case at the European Court initiated by Max Schrems, the judge deciced in October 2015 that Safe Harbour 1.0 does not protect European citizen enough.For example EU-citizen have reduced rights in a US court case when they want to complain.
So the EU has to negotiate a new Safe Harbour.
At February 1 there was a discussion in the European Parliament about a new Safe Harbour. However not much progress was made.
This blog has a good summary of the current status.