There are a lot of ideas of "meaning," and some relate to linguistics and some do not.
Some theories might work with meaning as a thing that exists independently of humans. This view puts meaning outside of linguistics. There are lots of various formulations of this, from Plato's idea that there is an ideal world of meaning, to the notion that the world is composed of entities, truth values, and functions between them, based on the works of Gottlob Frege (a view that allows for some cool linguistic semantics). In this sort of theory, words denote entities.
Other theories work with an idea of meaning as something constructed by humans, and therefore, how people use language can give insight into what they think the world means. For example, Ludwig Wittgenstein posits that words only mean something because they are used within specific "language games" and nothing that exists independently of them. Another such theory is George Lakoff's "Embodied Mind" - which states that all meaning is derived from things people can directly sense, or metaphors extended out from those bodily understandings.
Many types of linguistics do not need to stick to a full understanding of meaning, just how words, phrases, sentences, etc. relate to and express meaning, and can work no matter which definition of "meaning" you take. (And some don't even think that all utterances express meaning, but sometimes exist for other reasons, like to change the world, like J. L. Austin wrote about in How to Do Things with Words)