Complex sentence: The ideal diode has zero resistance for the "forward bias polarity", and infinite resistance (conducts zero current) for the "reverse voltage polarity"; if connected in an alternating current circuit, the semiconductor diode acts as an "electrical rectifier".
Split into simpler sentences: The ideal diode has zero resistance for the "forward bias polarity", and infinite resistance (conducts zero current) for the "reverse voltage polarity". In other words, the semiconductor diode acts as an "electrical rectifier".