Last can mean several different things:

1. To continue or endure for a period of time. A battery might last for six hours before needing a recharge. A friendship that lasts through disagreements and distance shows real strength. When you ask “How long will the movie last?” you're asking about its duration. Food that lasts stays fresh and edible: canned goods can last for years, while fresh strawberries last only a few days.
2. The final one in a series or sequence. The last page of a book completes the story. The last person to finish a race crosses the finish line after everyone else. When you're last in line, everyone else goes before you. Being last isn't always bad: sometimes the last slice of pizza is the best one, saved for the end.
3. Most recent or previous. Last week means the week that just passed. Your last birthday was the most recent one you celebrated. When someone mentions their last visit to the dentist, they mean the one that happened most recently before now.

The word connects to ideas of endings, persistence, and time. Something that lasts keeps going, while something that's last marks a conclusion or final position.