There are a couple different ways you could do that. The easiest would probably be a VLOOKUP formula. It will look for the value in the first column of the table and return the value from a column to the right.
=IF(B1="","",VLOOKUP(B1,$B$4:$C$175,2,0))
In this example: If B1 is blank, display nothing, otherwise find the value of B1 in the left-most column of the table B4:C175 and return the value from the 2nd column of the table (in this case, column C).