it's a broad term used to refer to any medical treatment that uses gene technology somehow.

there's mostly two variants today:

• mRNA medication. that one is temporary. it does something to you, then the effect wears off by itself within day, weeks or months. this one is new-ish (first used since around 2015) but it's getting more and more usage because it works well and has typically few side-effects.
• DNA-modifying medication. that one is permanent and possibly hereditary, i.e. it would affect your offspring too. a.f.a.i.k. it's practically not used today due to the grave and long-lasting impacts it would have on individuals and society.