multiple 'if-thens' (Chain Rule) with two sheets

I have attached a sample file with two sheets.

Sheet 1 has two columns, 'A' represents a parcel number, and 'B' represents an indicator for the plat name in which the parcel number is located.

Sheet 2 also has two columns. 'A' represents the same indicator as Sheet 1 Column 'B' and Column 'B' is the formal name for the plat.

What I hope to achieve is Sheet 1 Column 'A' to be the parcel number (as it currently is)and Column 'B' to be the formal name for the plat (instead of the number).

As you will notice, the plat numbers on Sheet 1 Column 'B' can repeat many times. A plat number of '0' would mean it is not associated with a plat and therefore should return a blank.

The 'real' file has over 275,000 parcel numbers. All total, there are approximately 8800 differnent plat names.

Thank you for considering and/or offering any advice.

Due to my 'lacking' skill level, I need it to be a macro as I have yet to learn other methods.