VLOOKUP allows you to browse a table for a particular cell value, and copy the contents of the cell a given number of columns beside it, explains Excel Easy. PMT allows you to calculate periodical payments, given a rate, amount of months to pay, starting value and future value.
There are various look up and reference functions in excel, but VLOOKUP, or vertical look up, allows you to search the leftmost column of a table for a specified value, returning a value in the same row, but a given number of columns to the right, explains Excel Easy. Variations include HLOOKUP, or horizontal look up, MATCH, INDEX and CHOOSE.
Similarly, PMT has various functions enabling you to calculate the parameters needed, such as RATE, NPER, PV and FV. PMT returns a calculated periodical payment based on the parameters specified above. RATE calculates the rate parameter of this function, given the others. NPER calculates the amount of months needed to pay off the PV, or present value, given the other parameters. PV calculates the initial amount to be paid with the other parameters. FV calculates the end value after the specified amount of payments, given the other parameters.