The name WordSwing is part of a metaphor for language learning. The words you learn are vines hanging in the jungle that you can use to swing to new vines (words), and thereby traverse the landscape (language-scape), in a fun, exhilarating, and effective way. You use the part of the language you know, to have meaningful language practice and thereby expand your understanding, swinging to ever higher levels of proficiency.
Consider the first part of the name, word. At WordSwing, there is a substantial focus on growing your vocabulary, as this is often the most important factor when understanding and communicating in real-life situations. So in this sense, words are your vehicle (or vines) to learn new things and get to new places. The focus on the word as the unit is also apparent in our estimate of your knowledge of the language. We track your learning at high resolution, down to your familiarity with individual words and even particular word usages. It is precisely this high resolution that enables us to propose relevant and accessible activities. A vine that you can't swing to is no use in exploring the jungle, and language that is not accessible is no help for learning.
Now for the second part, swing. Language learning should be fun and playful, and what better toy than a swing to capture the fun, playful nature of language. Language is amazing flexible and malleable; there are often many ways to say things, and thus language is an endlessly entertaining toy that can be played with in an infinite number of ways.