What does negative surprise mean?
(This is an English language question, not an economic one. Next time consider asking at English Language &amp; Usage.)
A surprise is negative, if it is a bad surprise (for someone). In this context they probably mean that the revealed value of the indicator (PMI) is lower than they expected, which shows that the economy is in worse shape than they expected.
(For different indicators, such as the unemployment rate, it could be that the negative surprise is a higher than expected value.)