The Change in Broker Consensus, 1 Month is the change in the consensus recommendation over the last month. Counter intuitively, 1 is scored as a Strong Buy, and 5 as a Strong sell. 3 is a Hold.
Negative numbers for this change in recommendation indicate improving sentiment. For example, if Change in Cons. Rec = 4, this indicates that in the last month the Cons. Rec has gone from strong buy to strong sell (1 to 5).
Alternatively, if Change in Cons. Rec = -1, this indicates that in the last month the Cons. Rec has moved towards buy by a single step. If it was a strong sell, the stock may now be an 'underperform'. If it was a hold, the stock may now be an 'outperform’.
A consensus recommendation for an individual stock compiles ratings from a number of analysts who track that stock. The recommendation is expressed as a median of the separate recommendations. ↵
A consensus recommendation provides a snapshot of current thinking about a stock, so it can serve as a benchmark against which you can compare a single analyst's opinion to gauge how mainstream it is. While recommendations aren't that useful in themselves, the change in recommendation is a powerful indicator - the direction of change being most important.
You can read more about recommendation revisions here.