That's correct. But in Perl 6 it's not restricted to methods, it also works on subroutines.

Basically it means that you have several routines (called "candidates" in p6 speak) with the same name but different signatures, and the closest match between the run-time argument list and the signatures determines the candidate to call

$ perl6 -e 'multi f(0) { 1 }; multi f(Int $x) {$x * f($x - 1) }; say f
+ 5'
120
[download]

The lack of subroutine signatures and user-exposed core types make it hard to introduce multis in Perl 5; but some of the current improvements and plans for Perl 5 make me hopeful that some day we'll have enough infrastructure to support them.

S06 has many more details on the Perl 6 multis.