Create 2 Filters for one collection (Shopify)

I’m trying to create 2 drop-down lists to filter one collection of products
I looked all over the internet and I couldn’t find a tutorial for that.

I know what I need to do but I don’t know how. So if you can, please, answer any of the following questions so I can move on with my code:

1. How can I create a drop-down list of all tags built in this structure: “PRODUCT_Socks”
2. How can I get the value selected in a drop-down list () and use it afterwards?
3. How can I hide the beginning of the tag? – hide the “PRODUCT_” so customers will only see “Socks”.

Thanks! 🙂