What does the third number in a NFL team's record stand for?
In American sports, such as American football played in the NFL, the three numbers generally represent wins-losses-ties. So a record of 36-20-1 means 36 wins, 20 losses and 1 tie. The exception to this is ice hockey in the NHL, in which the third number refers to overtime losses (since ties are no longer possible).
As shown on this Toronto FC supporters' forum post (an association football club in the MLS), this may lead to confusion for followers of European sports, as in Europe, the record is normally given as wins, draws and losses - i.e. a record of 50-5-40 means 50 wins, 5 draws and 40 losses.
Note that in European sports, the preferred term is draw (except in cricket, where both terms are used and have distinct meanings), while in American sports, the preferred term is tie.