If I transfer it would only be transferred half of my credits?

This is something that I’m thinking about and don’t get to understand. I study in Spain and if I want to transfer by the end of my first or second year, how would they take my credits? Because my course ends by May and I gotta apply by January for most of the colleges.
Then, by January, I’d only have half of my credits as much, so, do I have to apply and send them only half of my credits? Will they evaluate these? Will they take all of them if I get accepted by the end of the course?

I don’t understand how this works.

you first apply to a school. You send in your transcript prior to application deadline. Some (more selective schools) will ask for a midterm report which is about how you are doing in the semester prior to whatever semester you want to attend for that university. If you get accepted, you send in a final transcript after your last semester is over.

Each place decides for itself which credits will transfer. You might not know for certain until after you actually have enrolled and started classes.

When you communicate with the places on your transfer application list, ask them about their policies.