A Karnaugh-Veitch diagram is a tool used to simplify Boolean algebraic expressions. It looks like a little square made up of smaller squares (similar to a tic-tac-toe grid), and has a special system for assigning values to the squares.
When you have a Boolean expression with multiple variables, the Karnaugh-Veitch diagram helps you group together the combinations of variables that produce the same output (either True or False). You do this by assigning values to the squares that correspond to the different combinations of the variables.
Once you have all the squares labeled, you can look for patterns and groupings within the diagram. Any groupings of squares that contain only True values (i.e. all the variables in that grouping produce a True output) can be simplified to represent an entire section of the larger expression. This is a really useful tool for making large and complex Boolean expressions easier to understand and manipulate.