in database related document, parent and child is refer to what?

Question

that makes sense that we refer to the table that uses values from another table as a child(this column is defined as a foreign key), in this regard the other table is parent. this makes more sense in one to many relations. one record in the table(parent) has a relationship with one or more records in another table(child). in short terms one parent has many child.

in this answer from StackOverflow these were mentioned. but in this section of SQLAlchemy document that talks about many to one relationship, they are placing the ForeingKey in the parent table . what does it mean?

also in this section of SQLALchey document that talks about many to many relationship between two table, and implementing this behavior with Asociation object rather than Association table, they referring to one of the tables as parent and another one as child what does it mean?