Thanks to the popularity around the game, Minecraft Java has hundreds if not thousands of mods available for free online. It can range from spawning zombies or even rockets in the game to just improving performance with OptiFine.
In any video game, mods are software add-ons to enhance the gameplay experience by modifying original core elements. You can find out the differences between Minecraft Java and Bedrock right here.
Note: Keep in mind that installing Forge in Minecraft is limited to the Java edition.