Yes, "dba" means "doing business as". For example, if I had a doll shop, I might be "Sandra Sue dba The Doll Shop". This is a sole proprietorship. It makes it easier for someone to find the owner of a business.
I had a dba for years for my home-based business. A few years ago, I got another one in case I ever needed it for advertising since the name of the first one didn't quite fit. It is still good. They have to be renewed in ten years. I don't remember how much it cost me, but it is negligible. The paperwork is available at the county clerk's office, where it is filed. I needed the dba to get a business account at a bank. My current bank informs me that I cannot cash these Maritz checks to a business with my personal account. It used to be that I could just right the business name, then mine, and hand it to them. I'd hate to get a second account just for the sporadic checks from Maritz. I have enough to keep up with now: all my companies, my routing number for direct deposits, when PayPal money arrives into my account, my ADP login (required by only one company and it is their card and theirs alone) and how to cash it without having to pay anything, my credit cards for the demo company I work for, checking websites for when direct deposits arrive for those companies that don't notify me by email, and all of the receipts for everything I buy through mystery shopping or for business supplies. I don't have an accountant. Occasionally, I get a one-time debit card to use for a mystery shop so I can easily get a receipt.
The EIN, a substitute for the SSN when working, is easy to get.
With my merchandising companies, I have been asked variously to have auto insurance at a certain level, get a background check (an FBI check for one), and get a one-time drug test. I have my ID's on a memory card for uploading to the new companies I sign up with, and blank I-9's (citizenship papers) in a document file folder ready to use when asked. These are a cost of doing business. I'd hate to backtrack and do that for every single one of my many mystery shopping companies as well.