several years; a few years
Refers to an unspecified small number of years, typically more than two but not many. Common in both spoken and written Japanese.
He came to Japan a few years ago.
This project will probably take several years.
The research was carried out over several years.
I returned to my hometown for the first time in several years.
The new factory is expected to be completed within a few years.
We completed the project after several years of work.