The first number on each line is a unix time stamp. It represents the number of seconds since 1970.
This timestamp may be converted in EXCEL by using the following formula:
=(x+y)/86400+DATE(1970,1,1)
you can also ask perl to help by typing
perl -e 'print scalar localtime(x),"\n"'
x is the unix timestamp and y is the offset in seconds from UTC. (Perl knows y).