I’m sorry if this seems like a dumb question to ask but I’ve only been playing from 3 months so I don’t know everything.
So I’m looking at the skins you can buy and I noticed that some show but you can’t buy them and you can only get it from [insert special event] loot boxes. So is it possible to get skins that only available during a special event and you are able to get them every year or is it just one year you can get them
Sorry if this was confusing 
Yes - you can get these items when the specific event comes back. You can also get them in Anniversary lootboxes (Anniversary happens at the end of May).
As long as it’s a seasonal event, the skins return each year when the event comes around. 
EDIT: and to agree with sickone, also during Anniversary.
Yes you can. Events return every year and all items from that event are made available during it. This year Archives will not be returning, but you can still get those items, along with all other event items, during the Anniversary event.
We will still have Archives! There’s just no new PvE mode.