You do not need a record label to sell your music. There are many distribution services available to you to distribute your music on and offline. You are most likely to sell the majority of physical copies from your Merch table at a live show. High-end editions including vinyl can be incentives for a dedicated fanbase to purchase music. Crowdfunding campaigns with autographed copies also are a way of selling physical copies.
Traditionally record labels would pay for the studio time, make the records, package the records, distribute the records, market the records, promote records to radio, put artists on tour, provide advances, etc... However, you would owe the money spent. So whatever you had negotiated for a royalty would first be used to pay back that money. After that, you would receive royalties. However, the reality is that it is like a mortgage only once you have paid it off you still don't own your house. For this reason, a record deal really needs to be worth your while; you need to know they have the ability, resources, and interest to promote the record.
The reality is that with all the services available to artists it makes less and less sense to sign with a label. What is more, signing with a label is best if and when they come to you, not you desperately trying to get signed at all costs. The cream does rise to the top. If you are building your presence and making a name for yourself, chances are labels are aware of you already.
When you write your music and record your songs, you own the publishing and masters. That's a nice situation to be in. You're a one-stop-shop, which is appealing when it comes to licensing your music into TV and film.
A great way to sell your music is through crowdfunding campaigns. You need to be sure to have built an audience first. However, they make for a great way to find our album and make available special products and experiences to your fans. No need for a record label. Direct-to-fan.