General vocabulary is best thought of as the set of words useful to everyone who speaks a given language. This might include words about food, weather, and colors. Most people learn general vocabulary before words specific to a given industry or context, but the line between what is general and what is specific is often quite blurry. Usually, this term is merely a helpful category to use when learning or teaching languages.
When people learn to speak a language as a child or through immersion, vocabulary is usually integrated as it is used rather than through lists. As such, when people talk about general vocabulary, they are typically talking about learning a language in a class or other context. General vocabulary is almost always too basic to be useful on tests or in higher education, so this term rarely shows up outside of language learning contexts.
The types of words included in general vocabulary lists are usually highly functional. Words relating to food, directions, and other travel essentials are usually considered part of this type of vocabulary. In contrast, terms used in the sciences and literary terminology are typically not considered general. While many lists of general vocabulary are separated into topics, these topics themselves are almost always subjects that come up on a daily basis. These words are important for daily life, not for professional or academic purposes.
Among the topics typically included in general vocabulary, some are more general than others. Numbers, colors, and other words that relate to describing basic states of the world are almost always included in this type of vocabulary. Animals, furniture, and clothing items are more specific, but these are also usually considered basic enough to include. Broad categories of knowledge, such as words relating to history, time, and math, may be included as well, although for travelers this may not be very useful. Different age levels may need different basic vocabulary, and younger students often learn words relating to games and play, while older students learn about shopping or asking for directions.
On the one hand, it is useful for any language learner to establish a basic set of vocabulary words that can be used to create sentences for practice and actual use. Even so, many of the words often included in basic vocabulary lists are not useful to the people who need these words to talk. Animals, for example, are often included in general lists of vocabulary, but most people do not discuss geese and goats on a daily basis. Real, functional vocabulary can help keep language learners interested and is also easier to remember because it is more frequently used.