A harami is the opposite of an engulfing: a large candle followed by a small one whose body sits entirely inside the prior body. ("Harami" means pregnant — the big candle 'carrying' the small one.) On lower timeframes the same idea is called an inside bar.
What it signals
A harami says the prevailing momentum has suddenly stalled. After a strong push, a small contained candle means the dominant side could not extend — a pause that can precede a reversal or simply a consolidation. It is a loss of momentum, not yet a change of direction.
Trading the break
The harami itself does not tell you which way price goes — the break does. Many traders treat the inside candle's high and low as triggers: a close above the range resolves bullish, below resolves bearish. This makes the harami a clean, low-risk setup, because the opposite side of the inside bar is a tight invalidation.