Applicable means relevant or appropriate to a particular situation. When a rule is applicable, it applies to your circumstances. When advice is applicable, it actually fits your specific problem.

Think about a fire drill at school. The safety rules are applicable to everyone in the building, whether you're in the gym, the library, or a classroom. But the specific rule about “exit through the nearest door” looks different depending on where you are when the alarm sounds.

In science class, you might learn that certain formulas are only applicable to specific types of problems. The formula for finding the area of a circle isn't applicable when you're trying to find the volume of a cube. In everyday life, your parents' advice about handling friend drama might be highly applicable to your situation, while their stories about rotary phones probably aren't.

The word often appears in formal contexts: laws that are applicable in certain states, rules applicable to seventh graders but not sixth graders, or instructions applicable only to certain models of a product. When something isn't applicable, it simply doesn't apply to your situation, even if it's useful information in general. The key question is always: does this actually relate to what I'm dealing with right now?