The word tense has two main meanings:

1. A feeling of nervous strain or anxiety, like the tight, uncomfortable sensation before giving a speech or taking an important test. When you're tense, your muscles might feel tight and your body rigid, as if you're bracing for something difficult. A tense situation is one where people feel uneasy or worried, like when two friends have argued and haven't made up yet. The air feels thick and uncomfortable. You might notice your shoulders are tense after hunching over homework too long, or that a scary movie makes you feel tense throughout your whole body.
2. In grammar, tense tells you when something happens. The present tense describes what's happening now: “I walk to school.” The past tense describes what already happened: “I walked to school yesterday.” The future tense describes what will happen: “I will walk to school tomorrow.” Verbs change tense to show whether an action is happening in the past, present, or future. Learning to use tenses correctly helps you tell clear stories and explain when things occur.