Context
For our present purposes the simplest account of first order logic will suffice, i.e. one without function symbols and without any special treatment for equality.
See, for example, my semiformal description of first order logic.
The account in any text on first order logic is likely to suffice for present purposes.

Interpretation
The notion of interpretation is key.
An interpretation is an assignment to each relation symbol of a relation over the domain of discourse.
An interpretation may be thought of as a possible world.
The semantics is to be given by showing how the truth value of a sentence depends upon the structure of the particular world in which it is evaluated.


Satisfaction
It is the definition of the relationship of satisfaction which performs this role.
This is defined as a relationship between a sentence and an interpretation (in the context of an assignment of values to the free variables in the sentence, which we can ignore for present purposes).

Lack of Denotation
Because the semantics is presented as a relationship it does not appear to be denotational, there is no talk of "the meaning" of a sentence as an entity, no talk of propositions.
However, this can be done without changing the pragmatics of the semantics in any way.
A logically equivalent account can be presented in which each sentence denotes a proposition.


Propositions
In this alternative rendition of the semantics of first order logic we simply talk of the denotation of a sentence as the set of interpretations in which it is true, or as a "propositional function" which takes interpretations as arguments and yields truth values.
(still ignoring free variables)

