A stand-in for trivial, obvious, or boring content.
A put-down to silence someone who would otherwise not stop talking.
Used three times in a row, or in combination with other words, to indicate part of a sentence which would be annoying to include, or which is incomprehensible, or which is just unimportant.
One of a set of items which do not need to be specified; often used in conjunction with the catch phrase yadda yadda yadda.