It has 58 letters and is the name of a village in Anglesey, Wales.
Here's a breakdown of its meaning:
* Llanfair: St. Mary's
* pwll: pool
* gwyngyll: white hazel
* gogerychwyrndrobwllllantysiliogogogoch: the name of a church, which is itself a long and complex word.
It's worth noting that the word is not actually used very often in everyday conversation. People typically shorten it to "Llanfairpwll" or "Llanfair PG" for short.