But unto the sons
ben  (bane)
a son (as a builder of the family name), in the widest sense (of literal and figurative relationship, including grandson, subject, nation, quality or condition, etc.
of Kohath
Qhath  (keh-hawth')
allied; Kehath, an Israelite -- Kohath.
he gave
nathan  (naw-than')
to give, used with greatest latitude of application (put, make, etc.)
lo'  (lo)
not (the simple or abs. negation); by implication, no; often used with other particles (as follows)
because the service
`abodah  (ab-o-daw')
work of any kind -- act, bondage, + bondservant, effect, labour, ministering(-try), office, service(-ile, -itude), tillage, use, work, wrought.
of the sanctuary
qodesh  (ko'-desh)
a sacred place or thing; rarely abstract, sanctity -- consecrated (thing), dedicated (thing), hallowed (thing), holiness, (most) holy (day, portion, thing), saint, sanctuary.
belonging unto them was that they should bear
nasa'  (naw-saw')
to lift, in a great variety of applications, literal and figurative, absol. and rel. (as follows)
upon their shoulders
katheph  (kaw-thafe')
arm, corner, shoulder(-piece), side, undersetter.