"Their own" is commonly expressed as "their own" in Engpsh.
It is a possessive pronoun used to indicate that something belongs to or is associated with the subject.
Examples:
They have their own car. (他们有他们自己的车)
She made her own decision. (她做了她自己的决定)
They created their own business. (他们创办了他们自己的公司)