The LOOKUP function looks up for a value in a column or row and returns a corresponding value from the same position in another column or row. For example, if you know the name of a product but does not know its price, by using the LOOKUP function you can find the price of the product.
LOOKUP(lookup_value, lookup_vector, [result_vector])
The syntax has the following arguments:
lookup_value – Required. The value to look up. In our example, it is ‘Shirt’ which is a text value. It can be a number, text, a logical value, or name, or reference.
lookup_vector – Required. The range to search for lookup_value. It must be one column or one row.
[result_vector] – Optional. One column or one-row range from which you want to return the result. It must be the same size as the lookup_vector.
Note: The above example is based on the Vector form way. There are two ways to use the LOOKUP function: Vector form and Array form. Array form has limited functionality and often uses for compatibility purpose with other spreadsheets. Instead of using the Array form, use of VLOOKUP or HLOOKUP is recommended.
For more detail, you may visit Microsoft Official website.