This is somewhat dependent on the shell you use. What follows is valid for bash (and other recent shells).
`...` is the old, deprecated form of what is called "command substitution": it supplies the command's stdout in lieu of the command, to be assigned to
lines in this case.
man bash:
Quote:
Command Substitution
Command substitution allows the output of a command to replace the command name. There are two forms:
$(command)
or
`command`
The second line references the fourth element of the array
lines, to be assigned to the EDate variable. It probably will stay empty, as
lines, defined in the code line above, is a simple variable, not an array.