It’s a way of deriving an expression that gives you the output you want for given inputs.
If you have a small truth table, like for an AND gate, then it is easy to deduce the Boolean expression. AB = Y
But if you have a very large truth table, it may be too difficult to determine the Boolean expression without a K map.
If you meant though that you do not understand how to use a K map, let me know and I will explain.
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