This is a loop exit:

sub f { last; }

say "before loop";

{
   say "start of loop";
   f();
   say "end of loop";
}

say "after loop";
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({ ... } is technically a loop. You can also use while/until loop, a foreach loop, or a C-style for loop.)

This outputs

before loop
start of loop
Exiting subroutine via last at -e line 1.
after loop
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So the documentation you quoted refers to programs such as the following:

$SIG{ __DIE__ } = sub { last; };

say "before loop";

{
   say "start of loop";
   die "!";
   say "end of loop";
}

say "after loop";
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However, the code doesn't do what the documentation claims it does.

before loop
start of loop
Can't "last" outside a loop block at -e line 1.
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choroba pointed out that the documentation was corrected a short while ago.

However, the documentation is wrong, and it was corrected a short while ago. (Thanks to choroba for identifying this.)