Pivot points are specific price levels that can help traders predict the future direction of the market. Those price levels (or pivot points) are usually calculated based on the price action from the previous day. A pivot point is simply the average of the highest, lowest, and closing price of the previous day.
The average that is calculated based on various price levels from the previous day is the main pivot point. Other key levels are derived from that main pivot point based on specific formulas. Those other levels represent support and resistance levels that the price could react to. The main pivot point is usually called P whereas the other levels derived from it are called R1, R2, and R3 for resistance, and S1, S2...