了 in 我在这里两个星期了 / "I've been here for two weeks" What is the precise function of 了 in the sentence

我在这里两个星期了 / "I've been here for two weeks"


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Is it a marker of completed action? Is it saying "already"? What does the sentence mean if 了 were omitted?
我在这里两个星期了


了 here denotes a completion. It could be rendered with the perfect tense in English. Staying here for two weeks is completed, namely I have been here for two weeks(already).