A bullish divergence is seen at a market low. An example would be the Dow Jones Industrial Average going to a new low, but the S&P 500 failing to reach a new low. That’s a bullish divergence.
A bullish divergence can also be seen between price and an indicator. For example, EURUSD makes a new low, but RSI fails to reach a new low. That’s also a bullish divergence, and it’s a signal that prices may be resistant to further declines.