这是一家私人公司。

Zhè shì yì jiā sīrén gōngsī.

This is a private company.

这是我的私人物品，不要碰。

Zhè shì wǒ de sīrén wùpǐn, bùyào pèng.

This is my personal item, don't touch it.

这是私人领域，不方便他人进入。

Zhè shì sīrén lǐngyù, bù fāngbiàn tārén jìnrù.

This is a private area, it's not convenient for others to enter.