1. You can use it on almost everything--pants, bags and shoes.
2. You can use it on almost everything such as pants, bags and shoes.
(What is the function of '--' here? Does #1 mean #2?)
Yes, but 1 is less formal than 2.
"A dash is sometimes used to set off concluding lists and explanations in a more informal and abrupt manner than the colon. We seldom see the dash used this way in formal, academic prose."
http://grammar.ccc.commnet.edu/grammar/marks/dash.htm