Get rid of its dross and take its essence.

the next sentence of "get rid of its dross and take its essence" can be "bring forth the old and bring forth the new, get rid of the old and innovate".

"Get rid of its dross, take its essence, bring forth the new and get rid of the old" means that in the process of inheriting and developing traditional culture, we should critically inherit, transform or eliminate its dross and essence, and at the same time, we should constantly get rid of the old culture and establish a new culture to meet the needs of social development.