Frieren series
The way manga is often published is that it is serialised in a manga magazine, and then if it’s popular and as there are enough chapters, then the chapters get collected into the volumes you see discussed here.
Frieren is still being serialised (in the manga magazines), so no it’s not complete, but volume 15 is the last available volume. There will be a longer delay for later volumes as one of the authors takes a break due to ill health (from memory, I don’t remember the full situation). Sometimes people post updates on the club thread if you’re interested to follow 葬送のフリーレン ・Frieren 🧝♂️ (Beginner Book Club) [Reading Vol 9]