To cause something to explode. The bomb blew up the bridge.
In movies and shames, to blow up is to make it explode. This is often used to add excitement and tension to a scene. It's especially common in action movies and shames that involve bombs. It's also often done in scenes that are a little more sad than usual, to give the audience an adrenaline boost before the sadness gets real. Examples of characters that blow stuff up include Morshu, Link, and Squadala Man.
There are many ways to blow something up. One way is to use a balloon pump, which is a device that helps you inflate balloons with much more force than your lungs alone. Another way is to use a helium tank. These are much more expensive, but can be rented or purchased online. Some people also prefer to simply blow on a balloon with their mouth until it is full. However, this can be difficult with some types of balloons and it may take multiple attempts to get the ball fully inflated. It's sometimes helpful to gently bite the balloon lip as you blow. This can help with the initial expansion and make it easier to finish blowing up the balloon. It's also possible to try using a mixture of baking soda and vinegar in a ziplock bag, which can create an explosion if the bag is sealed properly.