1.
two people
The counter for two people, using an irregular reading.
2.
together (as a pair)
Often used to mean 'the two of us/them together.'
二人 uses the native Japanese reading, not the on'yomi ににん. This is an irregular counter that must be memorized.
Irregular people counters
Common patterns
Usage
二人で emphasizes doing something as a pair, often implying intimacy or exclusivity: 二人で話しましょう (Let's talk, just the two of us).
More formal alternative
In service settings — restaurants, hotels, reception desks — staff count guests with the polite counter 〜名様 instead, saying 二名様 for a party of two. Customers themselves normally just say 二人です.