Explanation
This formula uses the value in cell E5 for a lookup value, the named range "key" (H5:I9) for the lookup table, 2 to indicate "2nd column", and 0 as the last argument indicate exact match. You can also use FALSE instead of zero if you like.
VLOOKUP simply looks up the value and returns the group name from the 2nd column in the table. Both columns in the table can contain any values that you need, and the table doesn't need to be sorted since VLOOKUP is using exact match.
As always, if VLOOKUP can't find a match, it will return #N/A.
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VLOOKUP Function
The Excel VLOOKUP function is used to retrieve information from a table using a lookup value. The lookup values must appear in the first column of the table, and the information to retrieve is specified by column number. VLOOKUP supports approximate and exact matching...