Welcome to the forum.
The standard advice to someone in your position is to politely decline. A wedding is supposed to be a once in a lifetime event and recording those memories should be a high priority. It wouldn't be wise to ask a hobby pilot to fly a 747...and the same could be said for wedding photography.
You might offer to shoot a lot of stuff at her wedding, but suggest she hire a professional for the most important parts (usually the ceremony and formals).
That being said, a lot of people don't want to spend money for a professional photographer and would otherwise go without. If your friend truly understands your skill level and has reasonable expectations, the this might be a great opportunity for you to try your hand at wedding photography.
It should be said that the photographer is much more important than the gear they use...but having good equipment is certainly a good start. What do you shoot with?
As this is an event, you would need to be prepared for Murphy's Law and be able to get the job done. This means having backup equipment with you. At least two cameras, two flash units, lenses etc. Plenty of batteries and [film or memory cards] would be a good idea as well.