To confiscate something means to take it away from someone, usually as a punishment or because they weren't supposed to have it in the first place. When a teacher confiscates a student's phone during class, she takes it away because phones aren't allowed during lessons. When airport security confiscates a bottle of water, they take it because liquids over a certain size can't go through the checkpoint.

The word suggests official authority: parents, teachers, police officers, and other people in charge can confiscate things. You probably wouldn't say your little brother confiscated your video game controller, you'd say he took it or grabbed it. But a principal might confiscate contraband items like fireworks brought to school.

Confiscation is the noun form. If customs agents discover illegal goods, they carry out a confiscation, and the items become government property. Usually when something gets confiscated, there's a rule or law being enforced. Sometimes you get the item back later (like that phone after school ends), but sometimes confiscated items are kept permanently or even destroyed, especially if they're dangerous or illegal.