きり has two main uses. First, it means 'only' or 'just' when referring to a single instance or person, often with a nuance of incompleteness or finality. For example, 二人きり means 'just the two of us.' Second, it means 'since' or 'after' when attached to the past tense of a verb, indicating that since that past event, something has not happened or a state has continued. In this sense, it often pairs with negative endings like 〜ない to express that nothing has occurred since then.

This pattern is more common in written or formal speech, but you will hear it in conversation too. It can sound a bit literary or emphatic compared to more common alternatives like 〜だけ or 〜てから. Note that in the 'since' meaning, the verb before きり is always in plain past tense, and the second clause often shows a continuing state or a lack of change.