Hormone replacement therapy (HRT) replaces a hormone the body is short on. The two most common forms are menopausal hormone therapy (estrogen, usually with a progestogen) for women and testosterone replacement therapy (TRT) for men with hypogonadism.
HRT treats hormone-deficiency symptoms — not weight — and is a separate therapy from GLP-1 medications, though the two often come up together because menopause and low testosterone coincide with weight and body-composition changes. See the overview guide on HRT and GLP-1 medications for how they relate.