1. What does it mean?
홈트 shortens 홈 트레이닝, the Korean use of 'home training.' It refers to exercise done at home rather than going to a gym or class.
Also written or said as 홈 트레이닝, 홈트레이닝, home workout
2. The nuance
The word names the setting, not a fixed routine or training method. It may describe stretching, body-weight movements, or exercise with equipment. A 홈트 video is therefore a home-workout video, not necessarily a program suited to every viewer.
3. Examples
“오늘은 밖에 나갈 시간이 없어서 십 분만 홈트했어.”
I didn't have time to go out today, so I did a ten-minute workout at home.
“친구와 영상 통화를 켜 놓고 각자 홈트를 했어.”
My friend and I stayed on a video call while each doing a workout at home.
Sources
Korea Policy Briefing: language and culture
References support the meaning and usage. Example sentences are written for NoCapWiki.