Enzymes are mainly globular proteins - protein molecules where the tertiary structure has given the molecule a generally rounded, ball shape (although perhaps a very squashed ball in some cases). The other type of proteins (fibrous proteins) have long thin structures and are found in tissues like muscle and hair. We aren't interested in those in this topic.
These globular proteins can be amazingly active catalysts. You are probably familiar with the use of catalysts like manganese(IV) oxide in decomposing hydrogen peroxide to give oxygen and water. The enzyme catalase will also do this - but at a spectacular rate compared with inorganic catalysts.
One molecule of catalase can decompose almost a hundred thousand molecules of hydrogen peroxide every second. That's very impressive!
This is a model of catalase, showing the globular structure - a bit like a tangled mass of string