=SUM - sum of the cells selected or the value entered.
=IF - (sorry, can't explain it well) States if the logical question (thingy) is true or not.
=MIN - selects the least value of the value entered or among the cells selected.
=MAX - selects the greatest value among the value's entered or among the cells selected
=AVERAGE - finds the average of the values entered or of the cells selected.
Try it on MS Excel and you'll see. ☺
I hope it help. ☺