Welcome to the forum, sisymay. I'm still learning about how the publishing business works (mostly by reading the forum posts), but I have learned that you don't want to do business with publishers that make you pay, unless you've decided to self-publish, which is a whole different animal. Commercial publishers earn their revenue from selling books to readers, and part of that revenue is what they pay you.
However, there are plenty who earn their revenue by charging money to the authors of the books.
Before you sign on the dotted line or pay a cent to a publisher, spend time on the forum reading and learning and don't be afraid to search and ask questions about any publisher before signing with them.
Welcome, you've found a great place to learn.
Focus