Tāmen zài ɡōnɡyuán lǐ sānbù.

他们在公园里散步。

They went for a stroll in the park.


Notes:

他们(tāmen):they

在(zài): be at

公园(ɡōnɡyuán): park

里(lǐ): inside

散步(sānbù): walk for a stroll

Example:

A：他们去哪儿了？

     tāmen qù nǎér le？

     wher did they go?

B：他们在公园里散步。

     Tāmen zài ɡōnɡyuán lǐ sānbù.

     They went for a stroll in the park.