1.
Arr. is a written abbreviation for arrives . It is used on timetables to indicate what time a bus, train, or plane will reach a place.
...dep. Victoria 1927, ~ Ramsgate 2110.
2.
Arr. is a written abbreviation for arranged . It is used to show that a piece of music written by one person has been rewritten in a different way or for different instruments by another person.
‘A Good New Year’, sung by Kenneth McKellar, (Trad., Arr. Knight).