你永远是我的那个他你永远是我的那个她
[nĭ yŏng yuăn shì wŏ de nèi gè tā nĭ yŏng yuăn shì wŏ de nèi gè tā]
Literal translation is you'll always be that certain one I have (for he/gender not important). In most context, these words are sweet expressions used by couple indicating they think each other irreplaceable, unique presence.