Sure. Here is the definition of support and resistance levels.
http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:support_and_resistanThe charts on this page illustrate support and resistance levels and how they are interpreted as one part of technical analysis of stock prices.
Next, if we look at a current DJIA chart, we'll see that the DOW rallied from a short decline to 15739 (from Nov27 to Dec2) on Dec2, climbing to 16576 by year end.
In chart analysis, this Dec2 low point becomes a support level for future stock market declines. As long as these interim support levels aren't broken by future declines, the longer term trend remains in place, e.g., bullish in this specific case.
When a short term support level is broken, it's a short term bearish signal.
Now, obviously, support and resistance levels aren't an exact science. Nothing is when it comes to the stock market. From a technical analyst's perspective, it just means that there is a greater probability of the market going down to test the next support level than to reverse direction and immediately move up and set new highs. In this case, the next support level is around 15000, or to be specific, the 14803 low set on Oct9.
Of course, this depends on whether the DOW breaks this support level of 15739. A decline to 15000 (or 14803) is insignificant if you're a long term investor, but for traders, a 4.7% (or 5.9% if to 14803) decline is a big deal.