交朋友(jiāo péng yǒu) - to make friends in Mandarin

交朋友 (jiāo péng yǒu) means to make friends. 交 (jiāo) here means to form or establish a relationship, and 朋友 (péng yǒu) is "friend, friends".

The phrase is often paired with 容易 (róng yì, "easy") or 难 (nán, "difficult") to describe how easy or hard it is to make friends: 交朋友不容易 (jiāo péng yǒu bù róng yì), "making friends is not easy".

Do not confuse this 交 (jiāo) with the unrelated verb 教 (jiāo), "to teach". The two are written with different characters but share the same pronunciation and tone, so context has to carry the distinction.