But does it mean that the entity is the same thing than a row in my
No, not exactly. From the DDD perspective, an Entity is an element of the domain data model. It's part of the Ubiquitous Language. Read losttechies post about Entities.
DB rows are representations of the Entities states.
DDD does not state relationships 1-1 between DB rows and Entities. Quite the contrary. Abstract yourself from such detail.
The representations of a state could be stored in different rows, tables or why not, in different DBs. They could be stored in memory too, files, NoSQL DB's, etc
I mean there, can it exist objects between my Entities and my
database, like a representation of a database row, that will be
"converted" to my business entity?
Yes, It can. Whether to use ORMs (EF) or mere POCOS (Row-mappers) is implementation details.
I found vaughnvernon post to be very insightful. He exemplifies the approach with EF.
Especially this quote:
We are going to implement the Product Aggregate using two approaches.
One approach uses a Separated Interface with an implementation class,
and the other uses a domain object backed by a state object. The whole
point of these examples is to stay as far out of Entity Framework’s
way as possible.