Numbers 28 outlines the sacrificial offerings to be made to the Lord. In this context, the verse "one tenth for every lamb of the seven lambs" refers to the quantity of fine flour mixed with oil that was to be offered as a grain offering alongside each of the seven lambs sacrificed on specific days, especially the Sabbath and the beginning of each month.

Here's a breakdown:

"one tenth": This refers to one tenth of an ephah (a unit of measurement for dry goods). This is often interpreted as approximately 1/10 of a bushel.
"for every lamb": This specifies that the amount of flour mentioned above should be offered with each individual lamb.
"of the seven lambs": This indicates that this offering procedure applies to the daily burnt offering, which typically involved two lambs, one in the morning and one in the evening, and the additional five lambs offered during Sabbath and other special times.

In essence, the verse is a precise instruction about the ingredients of the grain offering accompanying each of the seven lambs sacrificed as part of the daily and special-day offerings.

So, for each of the seven lambs offered on days like the Sabbath or the beginning of the month, a grain offering consisting of one-tenth of an ephah of fine flour mixed with oil was also to be presented to the Lord. This served as an accompaniment to the burnt offering, symbolizing gratitude, devotion, and acknowledging God's provision.