"Zánmen 咱们" means "we; us". But "咱们" and "wǒmen 我们" (we; us) have different meanings. "咱们" refers to the people including the speaker and the listener, which may be only these two or couples of people involving both the two of them. "我们" also means two or more people that must include the speaker but not necessarily the listener. This may refer to the speaker himself and others (excluding the listener).
Note that both "咱们" and "我们" correspond to the Cantonese word "我哋", which means the Cantonese word "我哋" is broader in meaning than “咱们” and "我们" in Mandarin.
