A phrase's scope is the part of the sentence that that phrase's semantics apply to.
For example, the scope of a determiner that introduces a logical quantifier is the smallest clause it's in. This means that the interpretation of the quantification happens in that smallest clause, and not at the level of the entire sentence:
Shỏe jí kûq súq sıa rảı da.
means: “I allow you to say nothing.”
not: ❌ “There is nothing that I allow you to say.”
Here, the scope of sıa is the clause “kûq súq sıa raı”.
Topic and scope
If we want to say the other thing, we have to lift sıa out of the clause by placing it in the topic of the main clause:
Sıa rảı bı, shỏe jí kûq súq ráı da.
There is nothing that I allow you to say.
See Topic and focus in the refgram.
"Scoping over"
For two phrases X and Y, if the scope of X fully includes the scope of Y, then we say “X scopes over Y”.
This amounts to a claim about the order to apply their respective semantics in.
For example: high adverbials "scope over" the verb of the clause they're in. Thus, the sentence Dảı ní bũ da is interpreted as “this isn't possible” rather than “this is possibly false”.
Scope creep
One common beginner mistake is to rephrase sentences involving 
using a serial verb, under the impression that the meaning stays the same:
Shỏe jí kûq súq sıa rảı da.
“I allow you to say nothing.”
→ 🤔 Shỏe kủq jí súq sıa rảı da.
“I allow-to-say you nothing(?)”
However, the clause that was limiting the scope of sıa is now gone, which means that sıa scopes over the whole sentence. The meaning of the sentence is thereby changed to “There is nothing that I allow you to say”.