John Gill Commentary Numbers 4:24

"This is the service of the families of the Gershonites, in serving and in bearing burdens:" — Numbers 4:24 (ASV)

This [is] the service of the families of the Gershonites, to
serve, and for burdens .
The former of these phrases Aben Ezra interprets of setting up the tabernacle, making the bread (the shewbread), slaying (the sacrifices), and keeping, that is, watching and guarding, the tabernacle; and the latter of what they did when journeying, bearing and carrying the things assigned to them, afterwards mentioned.