"I'll tell you what" meaning in English

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          "ref": "c. 1596–1599 (date written), William Shakespeare, “The Second Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene i]:",
          "text": "My lord, I'll tell you what;/ If my young lord your son have not the day,/ Upon mine honour, for a silken point/ I'll give my barony: never talk of it.",
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        "Synonym of tell you what"
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          "word": "tell you what"
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  "word": "I'll tell you what"
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  "word": "I'll tell you what"
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