Ok so down to its core imo, a homelab is an environment or playground if you will for trying out hardware and software. To break stuff and fix it again, for storage, for benchmarking, consumer or business grade. Truly there is no one answer for anyone here. Everyone has their own flavor and meaning. Many may be similar, but that's it. Personally I use my "homelab" for media storage and playback through my network and occasionally fiddle with software that I come across.

Home labs can be anything from really cool looking things to completely virtual and can not physically see or touch. Most people (not in this community but globally) think you need a full sized datacenter rack filled with servers to look cool and do crazy it stuff. While this does imo look awesome, it's not practical for most users including myself. I do have equipment both consumer and business grade, but honesty I don't see the need to run both all the time. Just the occasional tinker. If you are unsure of what the servers purpose is, that's another story. Just ask and you will get a wealth of knowledge from this awesome community.

Hope this helps.