three: the cardinal number 3
This is simply the number three. It counts people, animals, objects, days, and amounts, and it works the way a counting word works in any language. Most of its hundreds of appearances are plain arithmetic: three sons, three days' journey, three hundred men, three measures of flour.
What makes three stand out in the Hebrew Bible is not a hidden second meaning but the way storytellers lean on it. A short, complete span of time is repeatedly "three days," and decisive turns often come "on the third day." Three is long enough to feel like a real wait and short enough to resolve quickly, so it became the storyteller's unit for a tense pause before a rescue or a verdict. Joseph holds his brothers three days, Jonah is in the fish three days, and a fast lasts three days. The number is doing narrative work, but it is still just the count three.
The one place the word shades into something a little different is when it counts how many times an action happens rather than how many things there are. "Three times a year" all Israel was to appear before the Lord; Balaam struck his donkey three times; God acts "twice, three times" to rescue a person. Here three measures repetitions, which is why it keeps the same core while answering a different question: not how many, but how often.