Because cache is the conjugated verb here.
The base form is cacher = to hide.
In this sentence, the subject is le bluff, which is third person singular, so the present tense of cacher is:
So:
French usually follows the same basic word order as English:
subject + verb + object
So in:
That means the bluff is doing the hiding, and the strategy is what is being hidden.
Yes, grammatically you could. But the meaning changes slightly.
So:
French often uses definite articles in places where English might be a little more flexible.
In Le bluff cache la stratégie, the sentence sounds like it is talking about the bluff and the strategy as identifiable concepts or as specific things in context.
This can happen in French when speaking about:
So even if English might sometimes prefer something like Bluffing hides strategy or A bluff hides strategy, French naturally uses Le and la here.
Grammatically, bluff here is a noun, not a verb.
So le bluff means the bluff or bluffing as a concept/tactic.
French often uses a noun with an article to express an idea that English might sometimes express with an -ing form. So depending on context, le bluff can feel like:
That depends on how broadly the sentence is being interpreted.