Complex sentence: Androgen replacement therapy (ART), often referred to as testosterone replacement therapy (TRT), is a class of hormone replacement therapy often prescribed to counter the effects of male hypogonadism.
Split into simpler sentences: Androgen replacement therapy (ART), often referred to as testosterone replacement therapy (TRT), is a class of hormone replacement therapy in which androgrens, often testosterone, are replaced. ART is often prescribed to counter the effects of male hypogonadism.