A complete topological vector space is a special kind of space where you can add and multiply things together, like numbers or vectors, but in a way that's kind of fancy and special. It's like a clubhouse for numbers and vectors, where they can hang out and do cool stuff together.
The "topological" part just means that we have some rules about when things are close together and when they're far apart. We use these rules to figure out how to move around in the space and how to get from one point to another.
But what makes a complete topological vector space really special is that it's "complete." This means that if we take a bunch of things in the space, like numbers or vectors, and keep adding them together in a certain way, we'll always get a new thing that's also in the space. And even better, if we keep doing this over and over again, we'll eventually get to a point where we can't add anything else in - we've reached the end! This is called the "limit" of the process.
So a complete topological vector space is like a super organized and fancy clubhouse for numbers and vectors, where they can all hang out and play together in a way that's really cool and special. And because it's complete, we know that whenever we start doing stuff with the things inside, we'll eventually get to a point where we're done and everything's all set.