3 Count all the men from thirty to fifty years of age who come to serve in the work at the tent of meeting.

Read Numbers 4:3 Using Other Translations

From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.
from thirty years old up to fifty years old, all who can come on duty, to do the work in the tent of meeting.
List all the men between the ages of thirty and fifty who are eligible to serve in the Tabernacle.