There is an adverb and pronoun used to indicate location or existence, often functioning as a level of emphasis in sentences. It can refer to a place, a point in discourse, or the existence of something; in American and other varieties, its pronunciation blends to a single, short vowel sound and a voiced interdental fricative, making it sound like “thair.” It’s common in casual speech and can contrast with “their” and “they’re.”
Full pronunciation guide