Being even more abstract than the sentence, the proposition is not only context-free but also language-free in the sense that it cannot be tied to any specific language. An utterance can be said or written in any language and recognized as a realization of a sentence of that particular language but the propositional meaning underpinning the utterance (and the sentence) is universal rather than language-specific.
In the analysis of the proposition, we find that the grammatical categories Subject, Object, etc., which served at sentence level do not apply and a pair of fundamental logical relationships is required: the predicate (state or action) and the argument (the entity or entities referred to by the predicate). In a little more detail, these expand into the processes (i.e. predicates) and roles (i.e. arguments) which are the focus of attention.
Perhaps a comparison of utterance, sentence and proposition with an example will be useful here; I can say (or write) the utterance (or text; the distinction seems rather illusive) in a limitless number of ways
A hit B with a hammer
or A hit B with a hammer
or A hit B with a hammer
or A HIT B WITH A HAMMER
or whatever, realizing – making substantial – a sentence with a SPOA structure in which the syntactic 'slots' (SPOA) are 'filled' by particular lexical items; A, hit, B, with a hammer rather than others, i.e. each of these is a realization of the same sentence (however written).
We might put this a little differently; saying the utterances (and the sentence they realize) all count as saying
I declare it to be the case that A hit B with a hammer
and in doing this, I am making a statement, asserting the existence of three entities – A, B and the hammer – and relationships between them and a process (hitting):
A (actor) hit (process) B (Goal) with a hammer (instrument)
The essential point here is that the Actor–Process–Goal–Instrument relationship of the proposition is identical for all languages, no matter how it is expressed syntactically.
If we express the same proposition in a number of languages (choosing suitable personal names for A and B), beginning with French, we get the written text: