11 Aaron is to present the Levites before the LORD as a wave offering from the Israelites, so that they may be ready to do the work of the LORD.

Read Numbers 8:11 Using Other Translations

And Aaron shall offer the Levites before the LORD for an offering of the children of Israel, that they may execute the service of the LORD.
and Aaron shall offer the Levites before the LORD as a wave offering from the people of Israel, that they may do the service of the LORD.
Raising his hands, Aaron must then present the Levites to the LORD as a special offering from the people of Israel, thus dedicating them to the LORD ’s service.