Language can be used to explain anything, that is what it is used for, just like telling a story about anything. In terms of the much more (multimodally) interesting question of capturing the same distinctions, then no, language does not 'explain' all the others... or even many of the others, because different things are going on.
Blogger Comments:
To be clear, on the SFL model, the 'different goings-on' in other human-only socio-semiotic systems are made possible by language, and it is through language that we analyse ('explain') them. Halliday & Matthiessen (1999: 3, 444):
All knowledge is constituted in semiotic systems, with language as the most central; and all such representations of knowledge are constructed from language in the first place.
… all of our experience is construed as meaning. Language is the primary semiotic system for transforming experience into meaning; and it is the only semiotic system whose meaning base can serve to transform meanings construed in other systems (including perceptual ones) and thus integrate our experience from all its various sources.
